|
Motorcycles » rec.motorcycles.dirt » Fouling Plugs on a '91 YZ250
| Fouling Plugs on a '91 YZ250 [message #770162] |
Tue, 11 July 2006 19:51 |
|
Hello all,
I've found a lot of useful information on this newsgroup and I
appreciate everyone's comments. I have a question about my '91 YZ250
that I just purchased. I've been fouling plugs like crazy in the few
weeks I've had it. The previous owner said that he fouled plugs as
well. The bike has a FMF pipe & silencer. I'm assuming the bike is
running way too rich because the plugs were coming out black and the
bike was making too much white smoke during rides. I leaned out the
gas from 30:1 (spec) to 40:1. Things looked and felt a whole lot
better during the test ride, but when I got back the plug was coated
black and looked like it was about to foul any minute.
So I'm assuming the jetting is messed up on the bike. I'm gussing the
previous owner didn't re-jet when he put the FMF pipe on. So I called
FMF & they gave the following specs:
Main: 370
Pilot: 45 (std)
Needle: Stock
Needle Position: 3rd
Air screw: 1.5 turns
The stock main jet on my bike was a 330. Say the previous owner didn't
re-jet after the pipe. Wouldn't that mean the bike should run lean on
a 330 main? I'm kind of at a loss for which direction I should go
next. I know the carb REALLY needs to be cleaned (probably hasn't been
in 15 years), but would this cause plug fouling? I was also going to
check & test different needle positions (try 2nd & 1st). It also idles
very poorly, so I was going to check the air screw. So if I find the
main to be 370, should I go leaner? Maybe all the way back to stock or
somewhere in between?
Thanks for the help.
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #770166 ] |
Tue, 11 July 2006 20:04 |
|
"Mike Beaty" <beatymj [at] gmail.com> wrote in message
news:1152640265.737680.247200 [at] 75g2000cwc.googlegroups.com...
> Hello all,
>
> I've found a lot of useful information on this newsgroup and I
> appreciate everyone's comments. I have a question about my '91 YZ250
> that I just purchased. I've been fouling plugs like crazy in the few
> weeks I've had it. The previous owner said that he fouled plugs as
> well. The bike has a FMF pipe & silencer. I'm assuming the bike is
> running way too rich because the plugs were coming out black and the
> bike was making too much white smoke during rides. I leaned out the
> gas from 30:1 (spec) to 40:1. Things looked and felt a whole lot
> better during the test ride, but when I got back the plug was coated
> black and looked like it was about to foul any minute.
>
> So I'm assuming the jetting is messed up on the bike. I'm gussing the
> previous owner didn't re-jet when he put the FMF pipe on. So I called
> FMF & they gave the following specs:
> Main: 370
> Pilot: 45 (std)
> Needle: Stock
> Needle Position: 3rd
> Air screw: 1.5 turns
>
> The stock main jet on my bike was a 330. Say the previous owner didn't
> re-jet after the pipe. Wouldn't that mean the bike should run lean on
> a 330 main? I'm kind of at a loss for which direction I should go
> next. I know the carb REALLY needs to be cleaned (probably hasn't been
> in 15 years), but would this cause plug fouling? I was also going to
> check & test different needle positions (try 2nd & 1st). It also idles
> very poorly, so I was going to check the air screw. So if I find the
> main to be 370, should I go leaner? Maybe all the way back to stock or
> somewhere in between?
>
> Thanks for the help.
>
Did you check the condition of the crank seals? On a bike that old, they are
always suspect. BTW, they can be replaced without dis-assembling the engine.
Tom
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #770169 ] |
Tue, 11 July 2006 20:30 |
|
Mike,
The age of your bike suggests that the problem may be one of a bad
ground or wire connection, or maybe even a stator.
Any fouled two stroke plug will look oily when you pull it. It gets
bathed in premix when the plug fouls.
White smoke usually means a coolant leak, getting into the
combustion chamber. I would check the head gasket.
You might also have a leaking crank seal (clutch side), which would
suck transmission oil into the combustion chamber, and cause oil
fouling of the spark plugs. Are you losing transmission oil?
Normally, extra oil in the Premix means a leaner air/fuel mixture,
since there is less gasoline per volume. I've seen bikes running 32/1
that had plugs which looked absolutely clean.
Leave the main jet alone, until you get further along with your
diagnostic process.
The FMF specs are only a general starting point. You will have to
fine tune it for your application, and adjust it for conditions. (This
is after you repack the silencer, and make sure that the rest of the
bike is okay).
A bad ground of the coil is the leading cause of plug fouling. Right
up there is a bad kill switch, or wire going to the kill switch.
(I've had both of these problems in the past.)
The spark plug wire/coil/cap junctions can get corroded and cause
premature plug failure. Poor connection of wires to the cdi can cause
the same.
A weak stator can cause plugs to die prematurely.
Good luck in your quest. It is all pretty simple, just time consuming.
Most of us have been there.
Jim Cook/Wudsracer
2006 GasGas DE300
******************************************
>On 11 Jul 2006 10:51:05 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>Hello all,
>
>I've found a lot of useful information on this newsgroup and I
>appreciate everyone's comments. I have a question about my '91 YZ250
>that I just purchased. I've been fouling plugs like crazy in the few
>weeks I've had it. The previous owner said that he fouled plugs as
>well. The bike has a FMF pipe & silencer. I'm assuming the bike is
>running way too rich because the plugs were coming out black and the
>bike was making too much white smoke during rides. I leaned out the
>gas from 30:1 (spec) to 40:1. Things looked and felt a whole lot
>better during the test ride, but when I got back the plug was coated
>black and looked like it was about to foul any minute.
>
>So I'm assuming the jetting is messed up on the bike. I'm gussing the
>previous owner didn't re-jet when he put the FMF pipe on. So I called
>FMF & they gave the following specs:
>Main: 370
>Pilot: 45 (std)
>Needle: Stock
>Needle Position: 3rd
>Air screw: 1.5 turns
>
>The stock main jet on my bike was a 330. Say the previous owner didn't
>re-jet after the pipe. Wouldn't that mean the bike should run lean on
>a 330 main? I'm kind of at a loss for which direction I should go
>next. I know the carb REALLY needs to be cleaned (probably hasn't been
>in 15 years), but would this cause plug fouling? I was also going to
>check & test different needle positions (try 2nd & 1st). It also idles
>very poorly, so I was going to check the air screw. So if I find the
>main to be 370, should I go leaner? Maybe all the way back to stock or
>somewhere in between?
>
>Thanks for the help.
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #770170 ] |
Tue, 11 July 2006 20:37 |
|
Thanks for your reply. I hadn't even considered an electrical problem
to be the culprit. I'll examine the electricals.
Also, there is a small crack in the tranny case right by the fill plug.
It looks like someone fixed it by sealing it with a clear glue or
sealer. Could this be causing transmission fluid (5w-20 in my case) to
be sucked into the engine?
Wudsracer wrote:
> Mike,
> The age of your bike suggests that the problem may be one of a bad
> ground or wire connection, or maybe even a stator.
>
> Any fouled two stroke plug will look oily when you pull it. It gets
> bathed in premix when the plug fouls.
>
> White smoke usually means a coolant leak, getting into the
> combustion chamber. I would check the head gasket.
>
> You might also have a leaking crank seal (clutch side), which would
> suck transmission oil into the combustion chamber, and cause oil
> fouling of the spark plugs. Are you losing transmission oil?
>
> Normally, extra oil in the Premix means a leaner air/fuel mixture,
> since there is less gasoline per volume. I've seen bikes running 32/1
> that had plugs which looked absolutely clean.
>
> Leave the main jet alone, until you get further along with your
> diagnostic process.
> The FMF specs are only a general starting point. You will have to
> fine tune it for your application, and adjust it for conditions. (This
> is after you repack the silencer, and make sure that the rest of the
> bike is okay).
>
> A bad ground of the coil is the leading cause of plug fouling. Right
> up there is a bad kill switch, or wire going to the kill switch.
> (I've had both of these problems in the past.)
>
> The spark plug wire/coil/cap junctions can get corroded and cause
> premature plug failure. Poor connection of wires to the cdi can cause
> the same.
> A weak stator can cause plugs to die prematurely.
>
> Good luck in your quest. It is all pretty simple, just time consuming.
> Most of us have been there.
>
> Jim Cook/Wudsracer
> 2006 GasGas DE300
>
> ******************************************
> >On 11 Jul 2006 10:51:05 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>
> >Hello all,
> >
> >I've found a lot of useful information on this newsgroup and I
> >appreciate everyone's comments. I have a question about my '91 YZ250
> >that I just purchased. I've been fouling plugs like crazy in the few
> >weeks I've had it. The previous owner said that he fouled plugs as
> >well. The bike has a FMF pipe & silencer. I'm assuming the bike is
> >running way too rich because the plugs were coming out black and the
> >bike was making too much white smoke during rides. I leaned out the
> >gas from 30:1 (spec) to 40:1. Things looked and felt a whole lot
> >better during the test ride, but when I got back the plug was coated
> >black and looked like it was about to foul any minute.
> >
> >So I'm assuming the jetting is messed up on the bike. I'm gussing the
> >previous owner didn't re-jet when he put the FMF pipe on. So I called
> >FMF & they gave the following specs:
> >Main: 370
> >Pilot: 45 (std)
> >Needle: Stock
> >Needle Position: 3rd
> >Air screw: 1.5 turns
> >
> >The stock main jet on my bike was a 330. Say the previous owner didn't
> >re-jet after the pipe. Wouldn't that mean the bike should run lean on
> >a 330 main? I'm kind of at a loss for which direction I should go
> >next. I know the carb REALLY needs to be cleaned (probably hasn't been
> >in 15 years), but would this cause plug fouling? I was also going to
> >check & test different needle positions (try 2nd & 1st). It also idles
> >very poorly, so I was going to check the air screw. So if I find the
> >main to be 370, should I go leaner? Maybe all the way back to stock or
> >somewhere in between?
> >
> >Thanks for the help.
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #770171 ] |
Tue, 11 July 2006 20:41 |
|
|
What oil are you running???
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #770172 ] |
Tue, 11 July 2006 20:46 |
|
I'm running Yamalube 2-r in the mix at 40:1 (previously 30:1). In the
transmission I'm running 5w-20.
Chris Buckley wrote:
> What oil are you running???
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #770201 ] |
Wed, 12 July 2006 00:03 |
|
You are very welcome.
The crack won't cause the problem, unless it is located where the
crank seal seats.
I would fill the crack (if it is non structural) with Quick Steel.
Jim
>On 11 Jul 2006 11:37:27 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>Thanks for your reply. I hadn't even considered an electrical problem
>to be the culprit. I'll examine the electricals.
>
>Also, there is a small crack in the tranny case right by the fill plug.
> It looks like someone fixed it by sealing it with a clear glue or
>sealer. Could this be causing transmission fluid (5w-20 in my case) to
>be sucked into the engine?
>
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #770258 ] |
Wed, 12 July 2006 05:42 |
|
In article <1152640265.737680.247200 [at] 75g2000cwc.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> Hello all,
>
> I've found a lot of useful information on this newsgroup and I
> appreciate everyone's comments. I have a question about my '91 YZ250
> that I just purchased. I've been fouling plugs like crazy in the few
> weeks I've had it. The previous owner said that he fouled plugs as
> well. The bike has a FMF pipe & silencer. I'm assuming the bike is
> running way too rich because the plugs were coming out black and the
> bike was making too much white smoke during rides. I leaned out the
> gas from 30:1 (spec) to 40:1. Things looked and felt a whole lot
> better during the test ride, but when I got back the plug was coated
> black and looked like it was about to foul any minute.
>
> So I'm assuming the jetting is messed up on the bike. I'm gussing the
> previous owner didn't re-jet when he put the FMF pipe on. So I called
> FMF & they gave the following specs:
> Main: 370
> Pilot: 45 (std)
> Needle: Stock
> Needle Position: 3rd
> Air screw: 1.5 turns
>
> The stock main jet on my bike was a 330. Say the previous owner didn't
> re-jet after the pipe. Wouldn't that mean the bike should run lean on
> a 330 main? I'm kind of at a loss for which direction I should go
> next. I know the carb REALLY needs to be cleaned (probably hasn't been
> in 15 years), but would this cause plug fouling? I was also going to
> check & test different needle positions (try 2nd & 1st). It also idles
> very poorly, so I was going to check the air screw. So if I find the
> main to be 370, should I go leaner? Maybe all the way back to stock or
> somewhere in between?
>
> Thanks for the help.
For your '91, check the existing jetting on your carb first. (It's not clear
what your carb's current jetting settings are.) I think stock specs are:
Main: 330
Pilot jet: 45
Needle: ? (check your manual. If you don't have one, buy the Yamaha owner's
manual before you do anything else.)
Needle position:?
Air Screw:?
It looks like FMF gave you some generic specs that don't have anything to do
with your specific model. In my experience, 2-stroke pipes don't necessarily
require jetting changes nearly as much as things like air temp and elevation and
humidity.
Next, repack the silencer and make sure the perforated pipe isn't clogged with
carbon. A spooge soaked silencer can make it difficult to jet correctly.
Now, you need to rule out leaking crank seals, which can cause poor running by
either allowing trans oil to get into the crank, or air. The best way I've found
is a leak down tester. I made one with some pvc fittings, a pressure
gauge/schraeder valve, and test cap from a plumbing supply store. Cap the
exhaust port of the cylinder, remove the carb and connect the pressure
gauge/valve into the rubber intake boot. Pump up the engine with 10 psi, and see
if it holds.
Once you know you've got free-flowing exhaust, and no seal leakage, start by
tuning the pilot circuit first, once that's optimized go to the jet needle clip
adjustments. Finally, work on the main jet but I've found that normally doesn't
come into play unless you're making a drastic change in elevation. Here's a
pretty good article on jetting,
http://www.motocross.com/motoprof/moto/mcycle/carb101/carb10 1.html although
ignore the advice on starting with main jet tuning. The Yamaha manual has a
pretty good description of when each of the jetting circuits come into play.
Good luck,
--
Charles
'99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777761 ] |
Wed, 12 July 2006 20:13 |
|
"Mike Beaty" <beatymj [at] gmail.com> wrote in message
news:1152640265.737680.247200 [at] 75g2000cwc.googlegroups.com...
> Hello all,
I leaned out the
> gas from 30:1 (spec) to 40:1.
> Thanks for the help.
You made it richer, not leaner.
To lean the gas, you would go from 30:1 to 25:1
I found on my CR125r that if I add more oil to the mix (leaning it) it has
less chance of fouling.
David
*Does not DESERVE a horse*
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777814 ] |
Thu, 13 July 2006 14:47 |
|
So adding more oil to the premix would make the chances of the spark
plug fouling go down? It seems like if there were less oil in the
mixture, the plug would burn hotter & cleaner, thus leaving less
residue on the spark plug and lessen the chances of a fouled plug.
David wrote:
> "Mike Beaty" <beatymj [at] gmail.com> wrote in message
> news:1152640265.737680.247200 [at] 75g2000cwc.googlegroups.com...
> > Hello all,
> I leaned out the
> > gas from 30:1 (spec) to 40:1.
>
>
> > Thanks for the help.
>
>
> You made it richer, not leaner.
>
>
> To lean the gas, you would go from 30:1 to 25:1
>
> I found on my CR125r that if I add more oil to the mix (leaning it) it has
> less chance of fouling.
>
> David
> *Does not DESERVE a horse*
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777815 ] |
Thu, 13 July 2006 14:57 |
|
I pulled the gas tank off last night and found something interesting.
The ground box (don't know exactly what it's called) that is screwed to
the frame has rusted connectors. I'm going to pull this off, clean it
up and hope that I get a better spark because of it. It seems like
that could be contributing to my fouling plugs. Also, I need to
further examine the wiring on the bike and clean it up. It's quite the
hack-job of wires & electrical tape. I also cleaned up the carb &
soaked it overnight in carb cleaner. I'm hoping this will solve my
plug fouling issues.
-Mike
Wudsracer wrote:
> Mike,
> The age of your bike suggests that the problem may be one of a bad
> ground or wire connection, or maybe even a stator.
>
> Any fouled two stroke plug will look oily when you pull it. It gets
> bathed in premix when the plug fouls.
>
> White smoke usually means a coolant leak, getting into the
> combustion chamber. I would check the head gasket.
>
> You might also have a leaking crank seal (clutch side), which would
> suck transmission oil into the combustion chamber, and cause oil
> fouling of the spark plugs. Are you losing transmission oil?
>
> Normally, extra oil in the Premix means a leaner air/fuel mixture,
> since there is less gasoline per volume. I've seen bikes running 32/1
> that had plugs which looked absolutely clean.
>
> Leave the main jet alone, until you get further along with your
> diagnostic process.
> The FMF specs are only a general starting point. You will have to
> fine tune it for your application, and adjust it for conditions. (This
> is after you repack the silencer, and make sure that the rest of the
> bike is okay).
>
> A bad ground of the coil is the leading cause of plug fouling. Right
> up there is a bad kill switch, or wire going to the kill switch.
> (I've had both of these problems in the past.)
>
> The spark plug wire/coil/cap junctions can get corroded and cause
> premature plug failure. Poor connection of wires to the cdi can cause
> the same.
> A weak stator can cause plugs to die prematurely.
>
> Good luck in your quest. It is all pretty simple, just time consuming.
> Most of us have been there.
>
> Jim Cook/Wudsracer
> 2006 GasGas DE300
>
> ******************************************
> >On 11 Jul 2006 10:51:05 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>
> >Hello all,
> >
> >I've found a lot of useful information on this newsgroup and I
> >appreciate everyone's comments. I have a question about my '91 YZ250
> >that I just purchased. I've been fouling plugs like crazy in the few
> >weeks I've had it. The previous owner said that he fouled plugs as
> >well. The bike has a FMF pipe & silencer. I'm assuming the bike is
> >running way too rich because the plugs were coming out black and the
> >bike was making too much white smoke during rides. I leaned out the
> >gas from 30:1 (spec) to 40:1. Things looked and felt a whole lot
> >better during the test ride, but when I got back the plug was coated
> >black and looked like it was about to foul any minute.
> >
> >So I'm assuming the jetting is messed up on the bike. I'm gussing the
> >previous owner didn't re-jet when he put the FMF pipe on. So I called
> >FMF & they gave the following specs:
> >Main: 370
> >Pilot: 45 (std)
> >Needle: Stock
> >Needle Position: 3rd
> >Air screw: 1.5 turns
> >
> >The stock main jet on my bike was a 330. Say the previous owner didn't
> >re-jet after the pipe. Wouldn't that mean the bike should run lean on
> >a 330 main? I'm kind of at a loss for which direction I should go
> >next. I know the carb REALLY needs to be cleaned (probably hasn't been
> >in 15 years), but would this cause plug fouling? I was also going to
> >check & test different needle positions (try 2nd & 1st). It also idles
> >very poorly, so I was going to check the air screw. So if I find the
> >main to be 370, should I go leaner? Maybe all the way back to stock or
> >somewhere in between?
> >
> >Thanks for the help.
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777818 ] |
Thu, 13 July 2006 16:07 |
|
In article <1152795447.824996.57530 [at] m73g2000cwd.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> I pulled the gas tank off last night and found something interesting.
> The ground box (don't know exactly what it's called) that is screwed to
> the frame has rusted connectors. I'm going to pull this off, clean it
> up and hope that I get a better spark because of it. It seems like
> that could be contributing to my fouling plugs. Also, I need to
> further examine the wiring on the bike and clean it up. It's quite the
> hack-job of wires & electrical tape. I also cleaned up the carb &
> soaked it overnight in carb cleaner. I'm hoping this will solve my
> plug fouling issues.
>
Get a tube of dielectric grease too, and put a small amount on all the
connectors and screws that pass current after you've cleaned off the corrosion &
dirt. It'll help prevent further corrosion.
--
Charles
'99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777820 ] |
Thu, 13 July 2006 16:42 |
|
The oil thickens the mix.
The fuel mixture has to go through a small hole (Jet). The thicker mix goes
through slower. Making it more air, less fuel.
It is the GAS in the mix that fouls plugs, not the oil.
David
(I used to think it was the oil too until someone on this newsgroup a few
years back corrected me).
"Mike Beaty" <beatymj [at] gmail.com> wrote in message
news:1152794825.231976.305910 [at] i42g2000cwa.googlegroups.com...
> So adding more oil to the premix would make the chances of the spark
> plug fouling go down? It seems like if there were less oil in the
> mixture, the plug would burn hotter & cleaner, thus leaving less
> residue on the spark plug and lessen the chances of a fouled plug.
>
> David wrote:
>> "Mike Beaty" <beatymj [at] gmail.com> wrote in message
>> news:1152640265.737680.247200 [at] 75g2000cwc.googlegroups.com...
>> > Hello all,
>> I leaned out the
>> > gas from 30:1 (spec) to 40:1.
>>
>>
>> > Thanks for the help.
>>
>>
>> You made it richer, not leaner.
>>
>>
>> To lean the gas, you would go from 30:1 to 25:1
>>
>> I found on my CR125r that if I add more oil to the mix (leaning it) it
>> has
>> less chance of fouling.
>>
>> David
>> *Does not DESERVE a horse*
>
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777823 ] |
Thu, 13 July 2006 17:00 |
|
On Thu, 13 Jul 2006 09:42:36 -0500, "David" <David [at] K-O.com> wrote:
>The oil thickens the mix.
>The fuel mixture has to go through a small hole (Jet). The thicker mix goes
>through slower. Making it more air, less fuel.
>It is the GAS in the mix that fouls plugs, not the oil.
You are talking about viscosity. Although 3.2 oz of oil into 128 oz of
fuel will change the viscosity slightly, I doubt it makes much of a
difference in the fuel/air ratio through the jets.
It's a question of volume and simple math. At 40:1 you have 40 parts
of fuel to every part of oil. At 32:1, now you only have 32 parts of
fuel to the same amount of oil, resulting in a leaner fuel/air ratio.
IMO, we shouldn't use the terms "rich/lean" when speaking of fuel/oil
ratios as it is confusing to many.
>David
DJ
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777832 ] |
Thu, 13 July 2006 18:16 |
|
>From the research I have done on plug fouling everyone is saying that
if you're fouling plugs you are probably running too rich. To me it
seems like rich and lean can mean different things depending on what
you're talking about. Let me see if I have this all straight.
Things that affect fouling plugs:
* Check for bad grounds. Plug not firing strong enouch & not buring
off all of the fuel, thus causing a rich condition (too much fuel in
the combustion chamber for too long).
* Repack silencer. Exhaust not flowing well and causing a "rich"
condition, thus fouling plugs.
* Needle position. Moving up toward the 1st position will lean the
bike out.
* Main Jet / Pilot Jet. Decreasing the size of these jets will lean
things out & reduce fouling.
* Air Screw. Reducing the number of turns out will lean things out.
* Premix. More oil will lean out the bike & foul less plugs.
Someone please correct me if I'm off here & set me straight.
Thanks!
Mike
IdaSpode wrote:
> On Thu, 13 Jul 2006 09:42:36 -0500, "David" <David [at] K-O.com> wrote:
>
> >The oil thickens the mix.
> >The fuel mixture has to go through a small hole (Jet). The thicker mix goes
> >through slower. Making it more air, less fuel.
> >It is the GAS in the mix that fouls plugs, not the oil.
>
> You are talking about viscosity. Although 3.2 oz of oil into 128 oz of
> fuel will change the viscosity slightly, I doubt it makes much of a
> difference in the fuel/air ratio through the jets.
>
> It's a question of volume and simple math. At 40:1 you have 40 parts
> of fuel to every part of oil. At 32:1, now you only have 32 parts of
> fuel to the same amount of oil, resulting in a leaner fuel/air ratio.
>
> IMO, we shouldn't use the terms "rich/lean" when speaking of fuel/oil
> ratios as it is confusing to many.
>
> >David
>
> DJ
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777836 ] |
Thu, 13 July 2006 18:35 |
|
On 13 Jul 2006 09:16:36 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>* Needle position. Moving up toward the 1st position will lean the
>bike out.
Another confusing part, do you mean move the needle "up" or the needle
clip up. Moving the needle down will result in a leaner mixture. To do
this, you must move the clip up...
>* Main Jet / Pilot Jet. Decreasing the size of these jets will lean
>things out & reduce fouling.
>* Air Screw. Reducing the number of turns out will lean things out.
Air screw out = more air = leaner F/A mixture
Air screw in = less air = richer F/A mixture
Fuel screw is just the opposite of the above.
>Someone please correct me if I'm off here & set me straight.
>
>Thanks!
>Mike
DJ
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777843 ] |
Thu, 13 July 2006 19:27 |
|
In article <1152794825.231976.305910 [at] i42g2000cwa.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> So adding more oil to the premix would make the chances of the spark
> plug fouling go down? It seems like if there were less oil in the
> mixture, the plug would burn hotter & cleaner, thus leaving less
> residue on the spark plug and lessen the chances of a fouled plug.
Mike, playing with the oil ratio will NOT solve your problem. I had a
severe case of fouling too and found the solution (not a cure, a
solution that works well to this day, according to the new owner).
See, I'd put in a new plug BR8ES, 9ES, EG, you name it - and it would
run fine all day. But if the next day it would foul immediately or
shortly after firing up the 2s 250cc bike.
Tired of playing with the needle clip position, changing the jettings,
going from 32-1 to 46-1 and in between (also used yamalube 2R), cleaning
and repacking my exhaust pipe and just about anything else in the book,
I finally found a solution that worked. And it is silly simple.
Simply remove the plug at the end of the day after a ride (or if parking
hte bike for longer than an hour) then put in an old, fouled plug (I'm
sure you have dozens of these by now). Don't just lightly screw it by
hand, mainly to keep dust and dirt out. Next day put in the other plug
and ride.
I had also experimented in leaving the used plug in gasoline overnight.
But this isn't necessary. Just clean the black, slimy oily residue from
the plug you just removed after the day's ride with some cleanex. I
would also use a fine sand paper in the electrodes just to ensure the
oil residue wasn't coating it too badly. It worked wonders. I never
again had to buy another plug. Sold the bike since but the new owner
(who I'm in touch regularly) indicates that he continues to use this
technique and that it is working great for him.
He's running the bike as I was, R2 at 40:1, 91 or 92 octane gas. I think
I had left the needle in the middle position (not that this changes
anything) and with our elevation/climate changes it sometimes likes the
topmost position. But the key thing is to remove that spark plug after
you ride the bike.
PS: even after a new top end the bike would still foul plugs. As you can
see, I tried it all and nothing worked. Wonder if the wire thing as
suggested by the other guy could have been the reason but I never got
around to it, since I found a solution that worked.
PS2: nothing worse than running back to your truck at the start of a
race, with your fouled bike at the start line just prior to your race
and realizing you're out of new plugs - then running up and down the
pits asking for a loaner plug. God, I so don't miss those days. My new
bike never fouls them. what a relief.
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777845 ] |
Thu, 13 July 2006 19:53 |
|
On 13 Jul 2006 05:57:27 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>I pulled the gas tank off last night and found something interesting.
>The ground box (don't know exactly what it's called) that is screwed to
>the frame has rusted connectors. I'm going to pull this off, clean it
>up and hope that I get a better spark because of it. It seems like
>that could be contributing to my fouling plugs. Also, I need to
>further examine the wiring on the bike and clean it up. It's quite the
>hack-job of wires & electrical tape. I also cleaned up the carb &
>soaked it overnight in carb cleaner. I'm hoping this will solve my
>plug fouling issues.
>
>-Mike
All those are excellent things to do.
-k
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777897 ] |
Fri, 14 July 2006 08:26 |
|
In article <1152807396.438531.30880 [at] b28g2000cwb.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> >From the research I have done on plug fouling everyone is saying that
> if you're fouling plugs you are probably running too rich. To me it
> seems like rich and lean can mean different things depending on what
> you're talking about. Let me see if I have this all straight.
> Things that affect fouling plugs:
> * Check for bad grounds. Plug not firing strong enouch & not buring
> off all of the fuel, thus causing a rich condition (too much fuel in
> the combustion chamber for too long).
> * Repack silencer. Exhaust not flowing well and causing a "rich"
> condition, thus fouling plugs.
> * Needle position. Moving up toward the 1st position will lean the
> bike out.
> * Main Jet / Pilot Jet. Decreasing the size of these jets will lean
> things out & reduce fouling.
> * Air Screw. Reducing the number of turns out will lean things out.
> * Premix. More oil will lean out the bike & foul less plugs.
If you read my post from earlier today you'll see that I have done all
of the above (in some cases several times over) short of the wiring
possibility. None worked. Too much oil in the mix is NOT your problem.
Lean that thing too much (as in, don't add enough oil to the gas) and
you'll ruin your engine. I provided a solution in my post that as said,
is working well so far. Although I would look at the wiring issue first.
Other than that don't fall into the "too rich" concept and lean the
thing so much as to ruin your engine. It will not help you. It didn't
help me (at one point I have the needle in the max, I had a smaller
needle (main and the other one) and I run R2 at 46:1. Still fouled up.
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #777945 ] |
Fri, 14 July 2006 19:21 |
|
I would think that your suggestion would work the majority of the time.
The thing is, I don't want to have to pull out my plug after every
ride and scrub it down. IMO, if your bike is fouling plugs, there is
something wrong. I'm hoping to find a fix for the problem. I
definitely appreciate your advice on how to cope with the problem if I
cannot find the ultimate cause.
-Mike
Eat Dirt wrote:
> In article <1152807396.438531.30880 [at] b28g2000cwb.googlegroups.com>,
> "Mike Beaty" <beatymj [at] gmail.com> wrote:
>
> > >From the research I have done on plug fouling everyone is saying that
> > if you're fouling plugs you are probably running too rich. To me it
> > seems like rich and lean can mean different things depending on what
> > you're talking about. Let me see if I have this all straight.
> > Things that affect fouling plugs:
> > * Check for bad grounds. Plug not firing strong enouch & not buring
> > off all of the fuel, thus causing a rich condition (too much fuel in
> > the combustion chamber for too long).
> > * Repack silencer. Exhaust not flowing well and causing a "rich"
> > condition, thus fouling plugs.
> > * Needle position. Moving up toward the 1st position will lean the
> > bike out.
> > * Main Jet / Pilot Jet. Decreasing the size of these jets will lean
> > things out & reduce fouling.
> > * Air Screw. Reducing the number of turns out will lean things out.
> > * Premix. More oil will lean out the bike & foul less plugs.
>
> If you read my post from earlier today you'll see that I have done all
> of the above (in some cases several times over) short of the wiring
> possibility. None worked. Too much oil in the mix is NOT your problem.
> Lean that thing too much (as in, don't add enough oil to the gas) and
> you'll ruin your engine. I provided a solution in my post that as said,
> is working well so far. Although I would look at the wiring issue first.
> Other than that don't fall into the "too rich" concept and lean the
> thing so much as to ruin your engine. It will not help you. It didn't
> help me (at one point I have the needle in the max, I had a smaller
> needle (main and the other one) and I run R2 at 46:1. Still fouled up.
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #778001 ] |
Sat, 15 July 2006 06:52 |
|
In article <1152897673.593244.235660 [at] b28g2000cwb.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> I would think that your suggestion would work the majority of the time.
> The thing is, I don't want to have to pull out my plug after every
> ride and scrub it down. IMO, if your bike is fouling plugs, there is
> something wrong. I'm hoping to find a fix for the problem. I
> definitely appreciate your advice on how to cope with the problem if I
> cannot find the ultimate cause.
>
> -Mike
>
> Eat Dirt wrote:
> > In article <1152807396.438531.30880 [at] b28g2000cwb.googlegroups.com>,
> > "Mike Beaty" <beatymj [at] gmail.com> wrote:
> >
> > > >From the research I have done on plug fouling everyone is saying that
> > > if you're fouling plugs you are probably running too rich. To me it
> > > seems like rich and lean can mean different things depending on what
> > > you're talking about. Let me see if I have this all straight.
> > > Things that affect fouling plugs:
> > > * Check for bad grounds. Plug not firing strong enouch & not buring
> > > off all of the fuel, thus causing a rich condition (too much fuel in
> > > the combustion chamber for too long).
> > > * Repack silencer. Exhaust not flowing well and causing a "rich"
> > > condition, thus fouling plugs.
> > > * Needle position. Moving up toward the 1st position will lean the
> > > bike out.
> > > * Main Jet / Pilot Jet. Decreasing the size of these jets will lean
> > > things out & reduce fouling.
> > > * Air Screw. Reducing the number of turns out will lean things out.
> > > * Premix. More oil will lean out the bike & foul less plugs.
> >
> > If you read my post from earlier today you'll see that I have done all
> > of the above (in some cases several times over) short of the wiring
> > possibility. None worked. Too much oil in the mix is NOT your problem.
> > Lean that thing too much (as in, don't add enough oil to the gas) and
> > you'll ruin your engine. I provided a solution in my post that as said,
> > is working well so far. Although I would look at the wiring issue first.
> > Other than that don't fall into the "too rich" concept and lean the
> > thing so much as to ruin your engine. It will not help you. It didn't
> > help me (at one point I have the needle in the max, I had a smaller
> > needle (main and the other one) and I run R2 at 46:1. Still fouled up.
Yeah I agree that finding the source of the problem to be the right
thing to do. But I wanted to warn you of the dangers of falling into the
"too rich a mixture" fog that almost everyone seems to quickly point to.
As you could be without an engine.
In retrospect I wish I had known about the wiring possibility. Since I
tried absolutely everything else, that sounds like a plausible
possibility.
PS: changing the plug takes no more than 25 seconds once you do it
enough times. If nothing else..
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #778029 ] |
Sat, 15 July 2006 23:44 |
|
I just got done repacking the silencer and cleaning things up a bit. I
cleaned up the carb, and check ALL of the wiring. The wiring was fine.
I saw nothing to indicate any problems. So I fired the bike up with
30:1 mix and tuned the air screw. I got it to idle just right, a lot
better than it was before (about 3.5 turns, now 1.5 turns). So I went
off to test ride, a few good straightaways & a little woods. The bike
was running great so I headed back after 20 mins of run time. As soon
as I get back to the road...braat..braat. br....bike dies. Now I'm
totally frustrated. Could it be the jetting? Which way should I go
next.
Thanks!
Eat Dirt wrote:
> In article <1152897673.593244.235660 [at] b28g2000cwb.googlegroups.com>,
> "Mike Beaty" <beatymj [at] gmail.com> wrote:
>
> > I would think that your suggestion would work the majority of the time.
> > The thing is, I don't want to have to pull out my plug after every
> > ride and scrub it down. IMO, if your bike is fouling plugs, there is
> > something wrong. I'm hoping to find a fix for the problem. I
> > definitely appreciate your advice on how to cope with the problem if I
> > cannot find the ultimate cause.
> >
> > -Mike
> >
> > Eat Dirt wrote:
> > > In article <1152807396.438531.30880 [at] b28g2000cwb.googlegroups.com>,
> > > "Mike Beaty" <beatymj [at] gmail.com> wrote:
> > >
> > > > >From the research I have done on plug fouling everyone is saying that
> > > > if you're fouling plugs you are probably running too rich. To me it
> > > > seems like rich and lean can mean different things depending on what
> > > > you're talking about. Let me see if I have this all straight.
> > > > Things that affect fouling plugs:
> > > > * Check for bad grounds. Plug not firing strong enouch & not buring
> > > > off all of the fuel, thus causing a rich condition (too much fuel in
> > > > the combustion chamber for too long).
> > > > * Repack silencer. Exhaust not flowing well and causing a "rich"
> > > > condition, thus fouling plugs.
> > > > * Needle position. Moving up toward the 1st position will lean the
> > > > bike out.
> > > > * Main Jet / Pilot Jet. Decreasing the size of these jets will lean
> > > > things out & reduce fouling.
> > > > * Air Screw. Reducing the number of turns out will lean things out.
> > > > * Premix. More oil will lean out the bike & foul less plugs.
> > >
> > > If you read my post from earlier today you'll see that I have done all
> > > of the above (in some cases several times over) short of the wiring
> > > possibility. None worked. Too much oil in the mix is NOT your problem.
> > > Lean that thing too much (as in, don't add enough oil to the gas) and
> > > you'll ruin your engine. I provided a solution in my post that as said,
> > > is working well so far. Although I would look at the wiring issue first.
> > > Other than that don't fall into the "too rich" concept and lean the
> > > thing so much as to ruin your engine. It will not help you. It didn't
> > > help me (at one point I have the needle in the max, I had a smaller
> > > needle (main and the other one) and I run R2 at 46:1. Still fouled up.
>
> Yeah I agree that finding the source of the problem to be the right
> thing to do. But I wanted to warn you of the dangers of falling into the
> "too rich a mixture" fog that almost everyone seems to quickly point to.
> As you could be without an engine.
>
> In retrospect I wish I had known about the wiring possibility. Since I
> tried absolutely everything else, that sounds like a plausible
> possibility.
>
> PS: changing the plug takes no more than 25 seconds once you do it
> enough times. If nothing else..
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #778031 ] |
Sun, 16 July 2006 00:28 |
|
In article <1152999841.068121.120530 [at] b28g2000cwb.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> I just got done repacking the silencer and cleaning things up a bit. I
> cleaned up the carb, and check ALL of the wiring. The wiring was fine.
> I saw nothing to indicate any problems. So I fired the bike up with
> 30:1 mix and tuned the air screw. I got it to idle just right, a lot
> better than it was before (about 3.5 turns, now 1.5 turns). So I went
> off to test ride, a few good straightaways & a little woods. The bike
> was running great so I headed back after 20 mins of run time. As soon
> as I get back to the road...braat..braat. br....bike dies. Now I'm
> totally frustrated. Could it be the jetting? Which way should I go
> next.
>
You've got to be pretty systematic about this. There's another thread going on
here with similar problems. Adjusting the air screw isn't really the tool for
tuning the idle, and by turning it in you've richened the low speed circuit.. If
you've ruled out crank seal leaks, then the carb is probably set too rich. Start
with the pilot jet, because it is less risky--you're not going to seize the
piston by running too lean on the pilot circuit, while things are a lot more
critical with the main jet. Start with the air screw out say 2 turns; go two
steps leaner on the pilot and run it awhile. If this is an imrovement, go one or
two steps leaner and see. If it's worse, go one or two steps richer and see what
happens. Do this until you've got it optimized, then tackle the jet needle,
using same steps moving the clip. Chances are, by the time you've got this
sorted out, you won't be fouling plugs, and won't need to touch the main. But
it's important to rule out the crank seal leak first.
--
Charles
'99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #778033 ] |
Sun, 16 July 2006 01:24 |
|
On 15 Jul 2006 14:44:01 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>I just got done repacking the silencer and cleaning things up a bit. I
>cleaned up the carb, and check ALL of the wiring. The wiring was fine.
> I saw nothing to indicate any problems. So I fired the bike up with
>30:1 mix and tuned the air screw. I got it to idle just right, a lot
>better than it was before (about 3.5 turns, now 1.5 turns). So I went
>off to test ride, a few good straightaways & a little woods. The bike
>was running great so I headed back after 20 mins of run time. As soon
>as I get back to the road...braat..braat. br....bike dies. Now I'm
>totally frustrated. Could it be the jetting? Which way should I go
>next.
>
>Thanks!
>
>
My '97 YZ250 did something similar. I ended up going to a leaner
needle. I think it made up for the wear and tear caused by the
vibration of the needle against the seat which opened up the seat
over time. That coupled with about 2000 ASL and it was just too much
fuel for bike at mid throttle.
With your bike being a '91, the carbo could just be worn out. If your
carbo has a replaceable needle seat, I would definitely try to find
one. Otherwise, try a richer needle or replace the carbo.
Good luck!
Mike Baxter --------------- "All GasGas, All The Time"
2005 GasGas EC300, 2000 GasGas EC300, 1997 GasGas JXT270
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #778051 ] |
Sun, 16 July 2006 15:20 |
|
On Fri, 14 Jul 2006 00:26:04 -0600, Eat Dirt <no_email [at] no_email.no>
blathered:
>Other than that don't fall into the "too rich" concept and lean the
>thing so much as to ruin your engine. It will not help you. It didn't
>help me (at one point I have the needle in the max, I had a smaller
>needle (main and the other one) and I run R2 at 46:1. Still fouled up.
No wonder. You still had the stock pilot. Canadian genius at its best.
MX Tuner
'03 Honda CRF480R
'06 Suzuki Hayabusa 1300
'06 Nissan Titan LE
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785197 ] |
Mon, 17 July 2006 03:17 |
|
On 15 Jul 2006 14:44:01 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>I just got done repacking the silencer and cleaning things up a bit. I
>cleaned up the carb, and check ALL of the wiring. The wiring was fine.
> I saw nothing to indicate any problems. So I fired the bike up with
>30:1 mix and tuned the air screw. I got it to idle just right, a lot
>better than it was before (about 3.5 turns, now 1.5 turns). So I went
>off to test ride, a few good straightaways & a little woods. The bike
>was running great so I headed back after 20 mins of run time. As soon
>as I get back to the road...braat..braat. br....bike dies. Now I'm
>totally frustrated. Could it be the jetting? Which way should I go
>next.
>
>Thanks!
My bike dies on a hot climb up a ridge trail - I think the suspect
might be the stator. Once cooled off and back at the camp it
kicked-over and ran fine, it idled normally.
The thing to check next is roosting it around for a while to get it to
heat-up again, but I live in town and don't have any very easy means
to do that. The police station is about four blocks away.
Electrical stuff that goes bad under heat can cause this problem, we
think it's the old stator on my '97 KTM, which had to be cleaned of
gunk and accumulated crud since that's on the "leaky" side for KTM's.
-keith
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785217 ] |
Mon, 17 July 2006 14:22 |
|
After getting a little more time to work on the bike, I was able to
improve things a little bit. I dropped the needle to the first clip
position. I did this first b/c it didn't require a trip to the parts
store. The bike did run a lot better during the test ride. Much more
power throughout the powerband. It also "felt" leaner, however, once I
got it back home and pulled the plug out, it was still black and burnt
up. The plug was (just like always) covered in a dry black carbon
crust. It didn't foul though, and I was happy to not have to push the
bike back home. My next step from here is to go 2 steps leaner on the
pilot. I'm pretty familiar with knowing when the bike is too rich, how
can I tell if it's too lean?
Thanks,
Mike
HardWorkingDog wrote:
> In article <1152999841.068121.120530 [at] b28g2000cwb.googlegroups.com>,
> "Mike Beaty" <beatymj [at] gmail.com> wrote:
>
> > I just got done repacking the silencer and cleaning things up a bit. I
> > cleaned up the carb, and check ALL of the wiring. The wiring was fine.
> > I saw nothing to indicate any problems. So I fired the bike up with
> > 30:1 mix and tuned the air screw. I got it to idle just right, a lot
> > better than it was before (about 3.5 turns, now 1.5 turns). So I went
> > off to test ride, a few good straightaways & a little woods. The bike
> > was running great so I headed back after 20 mins of run time. As soon
> > as I get back to the road...braat..braat. br....bike dies. Now I'm
> > totally frustrated. Could it be the jetting? Which way should I go
> > next.
> >
>
> You've got to be pretty systematic about this. There's another thread going on
> here with similar problems. Adjusting the air screw isn't really the tool for
> tuning the idle, and by turning it in you've richened the low speed circuit.. If
> you've ruled out crank seal leaks, then the carb is probably set too rich. Start
> with the pilot jet, because it is less risky--you're not going to seize the
> piston by running too lean on the pilot circuit, while things are a lot more
> critical with the main jet. Start with the air screw out say 2 turns; go two
> steps leaner on the pilot and run it awhile. If this is an imrovement, go one or
> two steps leaner and see. If it's worse, go one or two steps richer and see what
> happens. Do this until you've got it optimized, then tackle the jet needle,
> using same steps moving the clip. Chances are, by the time you've got this
> sorted out, you won't be fouling plugs, and won't need to touch the main. But
> it's important to rule out the crank seal leak first.
>
> --
> Charles
> '99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785219 ] |
Mon, 17 July 2006 14:38 |
|
I also forgot to mention that I ruled out a crankseal leak. I drained
the trans oil and when emptied, it was the exact same amount that went
in.
Mike Beaty wrote:
> After getting a little more time to work on the bike, I was able to
> improve things a little bit. I dropped the needle to the first clip
> position. I did this first b/c it didn't require a trip to the parts
> store. The bike did run a lot better during the test ride. Much more
> power throughout the powerband. It also "felt" leaner, however, once I
> got it back home and pulled the plug out, it was still black and burnt
> up. The plug was (just like always) covered in a dry black carbon
> crust. It didn't foul though, and I was happy to not have to push the
> bike back home. My next step from here is to go 2 steps leaner on the
> pilot. I'm pretty familiar with knowing when the bike is too rich, how
> can I tell if it's too lean?
>
> Thanks,
> Mike
>
> HardWorkingDog wrote:
> > In article <1152999841.068121.120530 [at] b28g2000cwb.googlegroups.com>,
> > "Mike Beaty" <beatymj [at] gmail.com> wrote:
> >
> > > I just got done repacking the silencer and cleaning things up a bit. I
> > > cleaned up the carb, and check ALL of the wiring. The wiring was fine.
> > > I saw nothing to indicate any problems. So I fired the bike up with
> > > 30:1 mix and tuned the air screw. I got it to idle just right, a lot
> > > better than it was before (about 3.5 turns, now 1.5 turns). So I went
> > > off to test ride, a few good straightaways & a little woods. The bike
> > > was running great so I headed back after 20 mins of run time. As soon
> > > as I get back to the road...braat..braat. br....bike dies. Now I'm
> > > totally frustrated. Could it be the jetting? Which way should I go
> > > next.
> > >
> >
> > You've got to be pretty systematic about this. There's another thread going on
> > here with similar problems. Adjusting the air screw isn't really the tool for
> > tuning the idle, and by turning it in you've richened the low speed circuit.. If
> > you've ruled out crank seal leaks, then the carb is probably set too rich. Start
> > with the pilot jet, because it is less risky--you're not going to seize the
> > piston by running too lean on the pilot circuit, while things are a lot more
> > critical with the main jet. Start with the air screw out say 2 turns; go two
> > steps leaner on the pilot and run it awhile. If this is an imrovement, go one or
> > two steps leaner and see. If it's worse, go one or two steps richer and see what
> > happens. Do this until you've got it optimized, then tackle the jet needle,
> > using same steps moving the clip. Chances are, by the time you've got this
> > sorted out, you won't be fouling plugs, and won't need to touch the main. But
> > it's important to rule out the crank seal leak first.
> >
> > --
> > Charles
> > '99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785227 ] |
Mon, 17 July 2006 16:06 |
|
In article <1153138947.446026.243450 [at] m79g2000cwm.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> After getting a little more time to work on the bike, I was able to
> improve things a little bit. I dropped the needle to the first clip
> position. I did this first b/c it didn't require a trip to the parts
> store. The bike did run a lot better during the test ride. Much more
> power throughout the powerband. It also "felt" leaner, however, once I
> got it back home and pulled the plug out, it was still black and burnt
> up. The plug was (just like always) covered in a dry black carbon
> crust. It didn't foul though, and I was happy to not have to push the
> bike back home. My next step from here is to go 2 steps leaner on the
> pilot. I'm pretty familiar with knowing when the bike is too rich, how
> can I tell if it's too lean?
It gets hard to start, loses power. Kind of the same symptoms as too rich,
(except for fouling plugs) although the penalty for going too far is a ruined
top end. But generally you're not going to destroy anything from a too lean
pilot jet.
I'm assuming you started with a brand new plug for this test?
If you're making a trip to the parts store, get the next step leaner needle too,
since you're already at the #1 position. And a spare clip, too :)
You can also turn out the carb's air screw since this has the same effect as
going leaner on the pilot jet. If you're more than 3 or 4 turns out, then go to
a leaner pilot jet.
--
Charles
'99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785230 ] |
Mon, 17 July 2006 16:25 |
|
Yeah, I started with a brand new plug. I had been cleaning them with
sandpaper & carb cleaner, but for this test I started brand new. I'm
very suprised I didn't break the needle clip when changing positions,
I'm known to break things like that. I'm 3 turns out on the air screw,
so I'll get the #35 pilot jet which is 2 steps leaner. I'm hoping this
will do the trick...my wife is getting tired ot my daily "test and
tune" sessions.
HardWorkingDog wrote:
> In article <1153138947.446026.243450 [at] m79g2000cwm.googlegroups.com>,
> "Mike Beaty" <beatymj [at] gmail.com> wrote:
>
> > After getting a little more time to work on the bike, I was able to
> > improve things a little bit. I dropped the needle to the first clip
> > position. I did this first b/c it didn't require a trip to the parts
> > store. The bike did run a lot better during the test ride. Much more
> > power throughout the powerband. It also "felt" leaner, however, once I
> > got it back home and pulled the plug out, it was still black and burnt
> > up. The plug was (just like always) covered in a dry black carbon
> > crust. It didn't foul though, and I was happy to not have to push the
> > bike back home. My next step from here is to go 2 steps leaner on the
> > pilot. I'm pretty familiar with knowing when the bike is too rich, how
> > can I tell if it's too lean?
>
> It gets hard to start, loses power. Kind of the same symptoms as too rich,
> (except for fouling plugs) although the penalty for going too far is a ruined
> top end. But generally you're not going to destroy anything from a too lean
> pilot jet.
>
> I'm assuming you started with a brand new plug for this test?
>
> If you're making a trip to the parts store, get the next step leaner needle too,
> since you're already at the #1 position. And a spare clip, too :)
>
> You can also turn out the carb's air screw since this has the same effect as
> going leaner on the pilot jet. If you're more than 3 or 4 turns out, then go to
> a leaner pilot jet.
>
> --
> Charles
> '99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785232 ] |
Mon, 17 July 2006 16:28 |
|
In article <1153146313.492930.212850 [at] m79g2000cwm.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> Yeah, I started with a brand new plug. I had been cleaning them with
> sandpaper & carb cleaner, but for this test I started brand new. I'm
> very suprised I didn't break the needle clip when changing positions,
> I'm known to break things like that. I'm 3 turns out on the air screw,
> so I'll get the #35 pilot jet which is 2 steps leaner. I'm hoping this
> will do the trick...my wife is getting tired ot my daily "test and
> tune" sessions.
"Better a dirt bike than a new girlfriend" tm, HWD Inc., patent pending.
--
Charles
'99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785233 ] |
Mon, 17 July 2006 16:35 |
|
Hah, you're right. At least I'm in the garage & not at the local Motel
6.
HardWorkingDog wrote:
>
> "Better a dirt bike than a new girlfriend" tm, HWD Inc., patent pending.
>
> --
> Charles
> '99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785434 ] |
Wed, 19 July 2006 15:11 |
|
I made my way to the parts store and got a variety of jets for my carb.
Last night I did a little test & tune. When I put in the smaller
pilot, it was still a little rich, and the idle was way too high. I
threw a one step smaller main, and back to the stock pilot. Still rich
& high idle. I put in yet another step smaller main, still high idle,
clean on the top end. So, I think I have the top end figured out, it's
just the bottom end that is rich & idling funny. I adjusted the
throttle screw to 1 turn out, and it still idles like crazy. The air
screw was turned way out too, probably 4 turns. Shouldn't putting a
smaller pilot jet in make it idle slower? I just wanted to double
check that going from a #45 to a #40 pilot will lean out the bike. Is
that correct? Could I have messed something up in the carb while
taking it apart & putting it back together?
Thanks,
Mike
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785440 ] |
Wed, 19 July 2006 16:03 |
|
In article <1153314717.236749.324630 [at] m73g2000cwd.googlegroups.com>,
"Mike Beaty" <beatymj [at] gmail.com> wrote:
> I made my way to the parts store and got a variety of jets for my carb.
> Last night I did a little test & tune. When I put in the smaller
> pilot, it was still a little rich, and the idle was way too high.
Good start. Now, go one step smaller on the pilot again, and test. But first,
figure out why the idle is too high.
> I threw a one step smaller main, and back to the stock pilot. Still rich
> & high idle. I put in yet another step smaller main, still high idle,
> clean on the top end.
I'd hold off trying to change too many things at once. Your first step was
right. Now, you're muddying things up.
> So, I think I have the top end figured out, it's
> just the bottom end that is rich & idling funny. I adjusted the
> throttle screw to 1 turn out, and it still idles like crazy.
Not sure what you mean here.
> The air
> screw was turned way out too, probably 4 turns. Shouldn't putting a
> smaller pilot jet in make it idle slower? I just wanted to double
> check that going from a #45 to a #40 pilot will lean out the bike. Is
> that correct? Could I have messed something up in the carb while
> taking it apart & putting it back together?
>
Yep, the 40 pilot is leaner. The air screw adjustment shouldn't really affect
idle *speed*, but more the quality of the idle. The idle speed adjustment is
another device. On my Keihin, it's a black knurled disc near the top of the carb.
The idle being too high makes me worried. Could there be an air leak in the boot
between carb and reeds? Did you get the carb slide in backwards? (Don't be
insulted, it happens.) Throttle cable misrouted?
--
Charles
'99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785524 ] |
Thu, 20 July 2006 09:07 |
|
In article <i7fkb2dl6hppvkm24ou67a4b4ouc4vk9ii [at] 4ax.com>,
MX Tuner <mxtuner [at] nospam.comcast.net> wrote:
> On Fri, 14 Jul 2006 00:26:04 -0600, Eat Dirt <no_email [at] no_email.no>
> blathered:
>
>
> >Other than that don't fall into the "too rich" concept and lean the
> >thing so much as to ruin your engine. It will not help you. It didn't
> >help me (at one point I have the needle in the max, I had a smaller
> >needle (main and the other one) and I run R2 at 46:1. Still fouled up.
>
> No wonder. You still had the stock pilot. Canadian genius at its best.
>
> MX Tuner
> '03 Honda CRF480R
> '06 Suzuki Hayabusa 1300
> '06 Nissan Titan LE
American arrogance at its typical.. always making ASSumptions..
FYI (god, why do I even bother??) I had "the other one" as the stock -
just couldn't remember the name, ergo 'the other one'. Not hard to
figure out for most people, it surprises it escaped you, the self
proclaimed know-it-all of the two wheels world.
Which makes me wonder: for someone that is acclaimed to know so much
about dirt bikes, why have you not offered to share your wisdom with the
original poster? More of that arrogance at work?
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785539 ] |
Thu, 20 July 2006 14:27 |
|
Another test & tune session last night, and I still can't get a plug
that isn't black. I did first try to figure out the idle. The only
way I could get the idle to actually calm down was to turn the air
screw in all the way, and then back out about a half turn. I checked
the throttle cable, slide and other areas for leaks and found nothing
out of the ordinary. The slide was fully seated in the bottom of the
carb as it should be. I did not check the reeds. I don't even know
what I'm looking for on the reeds...just anything that looks broken I
guess. Would a broken reed cause high idle? I put in the two step
leaner pilot, still too rich...black plug. I then put in a two step
leaner main. That's all I had to mess with, so that's what I did. The
only positive out of this test was that I did actually lean things out
at full throttle. My buddy and I could both feel it. I think the main
needs to go back to where it was & I need to stop messing with it:)
So the air screw really isn't the way to adjust the idle, but it's the
only thing that worked. I know this made the bike richer, and probably
messed up my test. Am I way off on the idle adjustment? It seems like
ever since I started messing with the pilot, the idle has been high.
Even when I put the stock pilot back in, it was still high. Makes me
wonder if there is something else going on. Where is a good place to
have the air screw? Or is the air screw/pilot jet combo that you're
looking for?
HardWorkingDog wrote:
> In article <1153314717.236749.324630 [at] m73g2000cwd.googlegroups.com>,
> "Mike Beaty" <beatymj [at] gmail.com> wrote:
>
> > I made my way to the parts store and got a variety of jets for my carb.
> > Last night I did a little test & tune. When I put in the smaller
> > pilot, it was still a little rich, and the idle was way too high.
>
> Good start. Now, go one step smaller on the pilot again, and test. But first,
> figure out why the idle is too high.
>
> > I threw a one step smaller main, and back to the stock pilot. Still rich
> > & high idle. I put in yet another step smaller main, still high idle,
> > clean on the top end.
>
> I'd hold off trying to change too many things at once. Your first step was
> right. Now, you're muddying things up.
>
> > So, I think I have the top end figured out, it's
> > just the bottom end that is rich & idling funny. I adjusted the
> > throttle screw to 1 turn out, and it still idles like crazy.
>
> Not sure what you mean here.
>
> > The air
> > screw was turned way out too, probably 4 turns. Shouldn't putting a
> > smaller pilot jet in make it idle slower? I just wanted to double
> > check that going from a #45 to a #40 pilot will lean out the bike. Is
> > that correct? Could I have messed something up in the carb while
> > taking it apart & putting it back together?
> >
>
> Yep, the 40 pilot is leaner. The air screw adjustment shouldn't really affect
> idle *speed*, but more the quality of the idle. The idle speed adjustment is
> another device. On my Keihin, it's a black knurled disc near the top of the carb.
>
>
> The idle being too high makes me worried. Could there be an air leak in the boot
> between carb and reeds? Did you get the carb slide in backwards? (Don't be
> insulted, it happens.) Throttle cable misrouted?
>
> --
> Charles
> '99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785540 ] |
Thu, 20 July 2006 14:58 |
|
Mike,
I am sorry if I missed this before, but... did you check the engine
and intake for air leaks?
Jim
>On 20 Jul 2006 05:27:03 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>Another test & tune session last night, and I still can't get a plug
>that isn't black. I did first try to figure out the idle. The only
>way I could get the idle to actually calm down was to turn the air
>screw in all the way, and then back out about a half turn. I checked
>the throttle cable, slide and other areas for leaks and found nothing
>out of the ordinary. The slide was fully seated in the bottom of the
>carb as it should be. I did not check the reeds. I don't even know
>what I'm looking for on the reeds...just anything that looks broken I
>guess. Would a broken reed cause high idle? I put in the two step
>leaner pilot, still too rich...black plug. I then put in a two step
>leaner main. That's all I had to mess with, so that's what I did. The
>only positive out of this test was that I did actually lean things out
>at full throttle. My buddy and I could both feel it. I think the main
>needs to go back to where it was & I need to stop messing with it:)
>
>So the air screw really isn't the way to adjust the idle, but it's the
>only thing that worked. I know this made the bike richer, and probably
>messed up my test. Am I way off on the idle adjustment? It seems like
>ever since I started messing with the pilot, the idle has been high.
>Even when I put the stock pilot back in, it was still high. Makes me
>wonder if there is something else going on. Where is a good place to
>have the air screw? Or is the air screw/pilot jet combo that you're
>looking for?
>
>HardWorkingDog wrote:
>> In article <1153314717.236749.324630 [at] m73g2000cwd.googlegroups.com>,
>> "Mike Beaty" <beatymj [at] gmail.com> wrote:
>>
>> > I made my way to the parts store and got a variety of jets for my carb.
>> > Last night I did a little test & tune. When I put in the smaller
>> > pilot, it was still a little rich, and the idle was way too high.
>>
>> Good start. Now, go one step smaller on the pilot again, and test. But first,
>> figure out why the idle is too high.
>>
>> > I threw a one step smaller main, and back to the stock pilot. Still rich
>> > & high idle. I put in yet another step smaller main, still high idle,
>> > clean on the top end.
>>
>> I'd hold off trying to change too many things at once. Your first step was
>> right. Now, you're muddying things up.
>>
>> > So, I think I have the top end figured out, it's
>> > just the bottom end that is rich & idling funny. I adjusted the
>> > throttle screw to 1 turn out, and it still idles like crazy.
>>
>> Not sure what you mean here.
>>
>> > The air
>> > screw was turned way out too, probably 4 turns. Shouldn't putting a
>> > smaller pilot jet in make it idle slower? I just wanted to double
>> > check that going from a #45 to a #40 pilot will lean out the bike. Is
>> > that correct? Could I have messed something up in the carb while
>> > taking it apart & putting it back together?
>> >
>>
>> Yep, the 40 pilot is leaner. The air screw adjustment shouldn't really affect
>> idle *speed*, but more the quality of the idle. The idle speed adjustment is
>> another device. On my Keihin, it's a black knurled disc near the top of the carb.
>>
>>
>> The idle being too high makes me worried. Could there be an air leak in the boot
>> between carb and reeds? Did you get the carb slide in backwards? (Don't be
>> insulted, it happens.) Throttle cable misrouted?
>>
>> --
>> Charles
>> '99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785543 ] |
Thu, 20 July 2006 15:04 |
|
I haven't. What is the the best way to go about doing that? In a car,
I know you can spray carb cleaner around the intake to see if the
engine surges. Anything similar on a dbike?
-Mike
Wudsracer wrote:
> Mike,
> I am sorry if I missed this before, but... did you check the engine
> and intake for air leaks?
>
> Jim
>
>
> >On 20 Jul 2006 05:27:03 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>
> >Another test & tune session last night, and I still can't get a plug
> >that isn't black. I did first try to figure out the idle. The only
> >way I could get the idle to actually calm down was to turn the air
> >screw in all the way, and then back out about a half turn. I checked
> >the throttle cable, slide and other areas for leaks and found nothing
> >out of the ordinary. The slide was fully seated in the bottom of the
> >carb as it should be. I did not check the reeds. I don't even know
> >what I'm looking for on the reeds...just anything that looks broken I
> >guess. Would a broken reed cause high idle? I put in the two step
> >leaner pilot, still too rich...black plug. I then put in a two step
> >leaner main. That's all I had to mess with, so that's what I did. The
> >only positive out of this test was that I did actually lean things out
> >at full throttle. My buddy and I could both feel it. I think the main
> >needs to go back to where it was & I need to stop messing with it:)
> >
> >So the air screw really isn't the way to adjust the idle, but it's the
> >only thing that worked. I know this made the bike richer, and probably
> >messed up my test. Am I way off on the idle adjustment? It seems like
> >ever since I started messing with the pilot, the idle has been high.
> >Even when I put the stock pilot back in, it was still high. Makes me
> >wonder if there is something else going on. Where is a good place to
> >have the air screw? Or is the air screw/pilot jet combo that you're
> >looking for?
> >
> >HardWorkingDog wrote:
> >> In article <1153314717.236749.324630 [at] m73g2000cwd.googlegroups.com>,
> >> "Mike Beaty" <beatymj [at] gmail.com> wrote:
> >>
> >> > I made my way to the parts store and got a variety of jets for my carb.
> >> > Last night I did a little test & tune. When I put in the smaller
> >> > pilot, it was still a little rich, and the idle was way too high.
> >>
> >> Good start. Now, go one step smaller on the pilot again, and test. But first,
> >> figure out why the idle is too high.
> >>
> >> > I threw a one step smaller main, and back to the stock pilot. Still rich
> >> > & high idle. I put in yet another step smaller main, still high idle,
> >> > clean on the top end.
> >>
> >> I'd hold off trying to change too many things at once. Your first step was
> >> right. Now, you're muddying things up.
> >>
> >> > So, I think I have the top end figured out, it's
> >> > just the bottom end that is rich & idling funny. I adjusted the
> >> > throttle screw to 1 turn out, and it still idles like crazy.
> >>
> >> Not sure what you mean here.
> >>
> >> > The air
> >> > screw was turned way out too, probably 4 turns. Shouldn't putting a
> >> > smaller pilot jet in make it idle slower? I just wanted to double
> >> > check that going from a #45 to a #40 pilot will lean out the bike. Is
> >> > that correct? Could I have messed something up in the carb while
> >> > taking it apart & putting it back together?
> >> >
> >>
> >> Yep, the 40 pilot is leaner. The air screw adjustment shouldn't really affect
> >> idle *speed*, but more the quality of the idle. The idle speed adjustment is
> >> another device. On my Keihin, it's a black knurled disc near the top of the carb.
> >>
> >>
> >> The idle being too high makes me worried. Could there be an air leak in the boot
> >> between carb and reeds? Did you get the carb slide in backwards? (Don't be
> >> insulted, it happens.) Throttle cable misrouted?
> >>
> >> --
> >> Charles
> >> '99 YZ250
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785544 ] |
Thu, 20 July 2006 15:19 |
|
Mike Beaty wrote:
> I haven't. What is the the best way to go about doing that? In a car,
> I know you can spray carb cleaner around the intake to see if the
> engine surges. Anything similar on a dbike?
It is the same way on bikes, but I use WD40 instead of carb cleaner.
Re: reeds, you check them by removing cage and looking against light,
if they are not fully seated you will see light through the cage, reeds
are worn out. With the time, they flip up so many times they get "used"
to be a little lifted, not sealing properly...
-- Tiago
|
|
|
| Re: Fouling Plugs on a '91 YZ250 [message #785547 ] |
Thu, 20 July 2006 15:34 |
|
On 20 Jul 2006 05:27:03 -0700, "Mike Beaty" <beatymj [at] gmail.com> wrote:
>Another test & tune session last night, and I still can't get a plug
>that isn't black. I did first try to figure out the idle. The only
>way I could get the idle to actually calm down was to turn the air
>screw in all the way, and then back out about a half turn. I checked
>the throttle cable, slide and other areas for leaks and found nothing
>out of the ordinary. The slide was fully seated in the bottom of the
>carb as it should be. I did not check the reeds. I don't even know
>what I'm looking for on the reeds...just anything that looks broken I
>guess. Would a broken reed cause high idle? I put in the two step
>leaner pilot, still too rich...black plug. I then put in a two step
>leaner main. That's all I had to mess with, so that's what I did. The
>only positive out of this test was that I did actually lean things out
>at full throttle. My buddy and I could both feel it. I think the main
>needs to go back to where it was & I need to stop messing with it:)
>
>So the air screw really isn't the way to adjust the idle, but it's the
>only thing that worked. I know this made the bike richer, and probably
>messed up my test. Am I way off on the idle adjustment? It seems like
>ever since I started messing with the pilot, the idle has been high.
>Even when I put the stock pilot back in, it was still high. Makes me
>wonder if there is something else going on. Where is a good place to
>have the air screw? Or is the air screw/pilot jet combo that you're
>looking for?
You need to adjust the air screw to make it idle as fast as possible.
Then turn the idle down with the idle screw. The idle screw adjusts
where the slide stops. If you can't adjust the idle down to where it
dies your not adjusting the right screw, also if your setting the idle
with the air screw your not ever going to get it to run right.
First set the idle high with the idle screw, then adjust your air
screw to where the idle is running as high as it will go. Then back
off the idle screw to where you want it to idle. Note- if the air
screw is out more than 3 turns you need to go leaner on the pilot jet,
if your within 1/2 turn of all the way in, you need a richer pilot.
If you still have problems with erratic idle, check for air leaks.
Murray
>
>HardWorkingDog wrote:
>> In article <1153314717.236749.324630 [at] m73g2000cwd.googlegroups.com>,
>> "Mike Beaty" <beatymj [at] gmail.com> wrote:
>>
>> > I made my way to the parts store and got a variety of jets for my carb.
>> > Last night I did a little test & tune. When I put in the smaller
>> > pilot, it was still a little rich, and the idle was way too high.
>>
>> Good start. Now, go one step smaller on the pilot again, and test. But first,
>> figure out why the idle is too high.
>>
>> > I threw a one step smaller main, and back to the stock pilot. Still rich
>> > & high idle. I put in yet another step smaller main, still high idle,
>> > clean on the top end.
>>
>> I'd hold off trying to change too many things at once. Your first step was
>> right. Now, you're muddying things up.
>>
>> > So, I think I have the top end figured out, it's
>> > just the bottom end that is rich & idling funny. I adjusted the
>> > throttle screw to 1 turn out, and it still idles like crazy.
>>
>> Not sure what you mean here.
>>
>> > The air
>> > screw was turned way out too, probably 4 turns. Shouldn't putting a
>> > smaller pilot jet in make it idle slower? I just wanted to double
>> > check that going from a #45 to a #40 pilot will lean out the bike. Is
>> > that correct? Could I have messed something up in the carb while
>> > taking it apart & putting it back together?
>> >
>>
>> Yep, the 40 pilot is leaner. The air screw adjustment shouldn't really affect
>> idle *speed*, but more the quality of the idle. The idle speed adjustment is
>> another device. On my Keihin, it's a black knurled disc near the top of the carb.
>>
>>
>> The idle being too high makes me worried. Could there be an air leak in the boot
>> between carb and reeds? Did you get the carb slide in backwards? (Don't be
>> insulted, it happens.) Throttle cable misrouted?
>>
>> --
>> Charles
>> '99 YZ250
|
|
|
Gehe zu:
aktuelle Zeit: Sat Nov 22 11:44:19 CET 2008
Insgesamt benötigte Zeit, um die Seite zu erzeugen: 0.19574 Sekunden |
