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Motorcycles » rec.motorcycles.tech » Custom Exhaust
| Custom Exhaust [message #769212] |
Mon, 10 July 2006 18:59 |
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I went for a weekend bike trip this last weekend and right before
heading home I talked to a couple of other guys riding sport bikes.
Well, when I bought my Katana it had a Vance and Hines slip-on muffler.
This guy tried to tell me that because of the less restrictive
exhaust, I needed a jet kit on my carbs. Otherwise, my bike would run
too lean, and therefore too hot.
I'm pretty sure it isn't running hot enough to burn anything up
because it still runs pretty well and I've put 4,500 miles on it in the
15 months I've owned it. I was under the impression that free flowing
exhaust and Intake was required to get the desired effects. The Slip
on definitely sounds better, but is it helping? Would a K&N give me a
significant boost because I already have decent exhaust? Would a jet
kit be required or would the retune just involve changing the mixture
settings on the parts I have? I figure that the same old air filter
would have the same Carb pressure/velocity, therefore, the same
combustion. I suppose the pipes might change tuning, but if the
headers are the same, isn't the resonance the same too? I don't really
understand all this stuff and I thought it would be a good topic to
post about.
Thanks everyone,
Tim
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| Re: Custom Exhaust [message #769213 ] |
Mon, 10 July 2006 19:12 |
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2000 Suzuki katana gsx750f, 1984 Honda Magna V45 <fixit335 [at] excite.com> wrote:
> ... I don't really understand all this stuff and I thought it would
> be a good topic to post about.
A painfully accurate and concise description of usenet.
My 2 cents: If you really want to make your bike run the best it can,
take it to a knowledgeable tuner who has experience with your particular
bike *before you buy any parts*, and have him set up your bike and fine
tune it using a dynamometer and exhaust gas analyzer. Any other method
is a recipe for disappointment.
--
'01 SV650S '99 EX250-F13 '98 ZG1000A-13 '81 CM400T
OMF #7
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| Re: Custom Exhaust [message #769224 ] |
Tue, 11 July 2006 08:32 |
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"2000 Suzuki katana gsx750f, 1984 Honda Magna V45" <fixit335 [at] excite.com>
wrote in message
news:1152550769.275232.127870 [at] m79g2000cwm.googlegroups.com...
> I went for a weekend bike trip this last weekend and right before
> heading home I talked to a couple of other guys riding sport bikes.
> Well, when I bought my Katana it had a Vance and Hines slip-on muffler.
> This guy tried to tell me that because of the less restrictive
> exhaust, I needed a jet kit on my carbs.
Oh, brother.
> Otherwise, my bike would run
> too lean, and therefore too hot.
And I'll bet he had a jet kit right there he was just itching to sell you!
Next your going to be telling us this jet kit just so happend to be
on sale, just this week! How fortunate you are to have come in!
> I'm pretty sure it isn't running hot enough to burn anything up
so am I.
> because it still runs pretty well and I've put 4,500 miles on it in the
> 15 months I've owned it. I was under the impression that free flowing
> exhaust and Intake was required to get the desired effects. The Slip
> on definitely sounds better, but is it helping?
Probably not. If you were to do something logical, like, say DYNO it,
once with the slip-on on, once with it off, why then we might be getting
somewhere.
> Would a K&N give me a
> significant boost because I already have decent exhaust? Would a jet
> kit be required or would the retune just involve changing the mixture
> settings on the parts I have? I figure that the same old air filter
> would have the same Carb pressure/velocity, therefore, the same
> combustion. I suppose the pipes might change tuning, but if the
> headers are the same, isn't the resonance the same too? I don't really
> understand all this stuff and I thought it would be a good topic to
> post about.
>
I'm going to make just a few observations here. You won't like them
and I'm sure you won't believe them, but I'll make them anyway.
The factory already did a fairly good job of tuning your bike for
an all around ride. If you just add shit-can stuff to it, without
understanding
the tradeoffs the factory took, you will almost certainly make it have
less power.
What a tuner who knows that he's doing can do is change the bike so
that it fits DIFFERENT premises.
Suppose you -never- ride your bike when the temp is below 40 degrees,
and you don't live in the city, and never ride on any road with a speed
limit under 45Mph. This is a premise adjustment that the factory didn't
use when they setup your bike. A good tuner could tune your bike for
optimum power for this environment - it would run like shit if you tried to
ride it in the city, or he could tune it for optimal gas mileage - once
again
it would probably run like shit in the city.
A good tuner could also change the torque curve so that instead of having
decent torque through a range of speed from, say, 0 to 90Mph, all the
torque could be concentrated in the low end. You could then easily
smoke your tires when taking off from every stoplight - that is, if such
a thing is important to you. You would lose top end power, but who
cares - the looks are the thing, right?
What is it that you want? Do you think that the factory -deliberately-
does things to make their products run -slow- and that somehow by
adding all this aftermarket shit, that your going to free up some
horsepower that your being denied?
Bolt-on performance stuff like headers worked great for the "i don't
know what I'm doing but I wanna buy some performance gear for ma
bike anyway" crowd about 25 years ago when the factories regularly
did some really bizarre and stupid stuff - like 4 into 4
exhaust - that was done more for looks than anything else. And it
does sometimes work even today when dealing with motorcycles
like certain Harley models which have an exhaust system designed
solely to give the motorcycle a certain "sound". But, the people that
buy those kinds of motorcycles are actually buying them to get the
"sound" and therefore there's not much market for a system that
gets rid of the "custom sound" and gives you more power in exchange.
But today, generally the bolt-on stuff is a waste of money, unless your
going to completely change the entire setup on the bike - cam, timing,
intake, carbs, pistons, exhaust - in order to change the performance
premise the bike was setup on by the factory.
Ted
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| Re: Custom Exhaust [message #769225 ] |
Tue, 11 July 2006 08:43 |
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Ted Mittelstaedt <tedm [at] toybox.placo.com> wrote:
> But today, generally the bolt-on stuff is a waste of money, unless your
> going to completely change the entire setup on the bike - cam, timing,
> intake, carbs, pistons, exhaust - in order to change the performance
> premise the bike was setup on by the factory.
What he said.
However, there *are* bikes where the standard can is so restrictive (for
noise testing porpoises) that a simple swap can liberate a surprising
number of extra horses with no trade-off anywhere else. The old Suzuki
1200 Bandit (did you get that in the USA?) is one - we're talking
12-15bhp here, believe it or not.
A couple of Ducatis also come to mind. Not much else.
--
Trophy 1200 750SS CB400F CD250 Z650
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....
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| Re: Custom Exhaust [message #777671 ] |
Wed, 12 July 2006 20:08 |
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Thanks for all the input guys. No, the jet kit guy wasn't selling
anything, he just wanted to show off how cool he was for putting a jet
kit in the other guy's bike. I was pretty sure he was full of it, but
didn't have anything to really back that up. I don't think I have the
money to invest in aftermarket parts, especially now that I understand
more about them. I agree, the factory set up the bike for an all
around performance. I think that is fine for me, considering I'll
never make it to a track day. I don't think there is going to be
enough to gain from paying a tuner to make it worth my while and
especially my poor college student cash. Thanks for the advice
everyone!
Tim
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| Re: Custom Exhaust [message #777675 ] |
Wed, 12 July 2006 23:42 |
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Ted Mittelstaedt schreef:
> "2000 Suzuki katana gsx750f, 1984 Honda Magna V45" <fixit335 [at] excite.com>
> wrote in message
> news:1152550769.275232.127870 [at] m79g2000cwm.googlegroups.com...
> > I went for a weekend bike trip this last weekend and right before
> > heading home I talked to a couple of other guys riding sport bikes.
> > Well, when I bought my Katana it had a Vance and Hines slip-on muffler.
> > This guy tried to tell me that because of the less restrictive
> > exhaust, I needed a jet kit on my carbs.
>
<SNIP>
> The factory already did a fairly good job of tuning your bike for
> an all around ride. If you just add shit-can stuff to it, without
> understanding
> the tradeoffs the factory took, you will almost certainly make it have
> less power.
>
> What a tuner who knows that he's doing can do is change the bike so
> that it fits DIFFERENT premises.
>
> Suppose you -never- ride your bike when the temp is below 40 degrees,
> and you don't live in the city, and never ride on any road with a speed
> limit under 45Mph. This is a premise adjustment that the factory didn't
> use when they setup your bike. A good tuner could tune your bike for
> optimum power for this environment - it would run like shit if you tried to
> ride it in the city, or he could tune it for optimal gas mileage - once
> again
> it would probably run like shit in the city.
>
> A good tuner could also change the torque curve so that instead of having
> decent torque through a range of speed from, say, 0 to 90Mph, all the
> torque could be concentrated in the low end. You could then easily
> smoke your tires when taking off from every stoplight - that is, if such
> a thing is important to you. You would lose top end power, but who
> cares - the looks are the thing, right?
>
> What is it that you want? Do you think that the factory -deliberately-
> does things to make their products run -slow- and that somehow by
> adding all this aftermarket shit, that your going to free up some
> horsepower that your being denied?
>
> Bolt-on performance stuff like headers worked great for the "i don't
> know what I'm doing but I wanna buy some performance gear for ma
> bike anyway" crowd about 25 years ago when the factories regularly
> did some really bizarre and stupid stuff - like 4 into 4
> exhaust - that was done more for looks than anything else. And it
> does sometimes work even today when dealing with motorcycles
> like certain Harley models which have an exhaust system designed
> solely to give the motorcycle a certain "sound". But, the people that
> buy those kinds of motorcycles are actually buying them to get the
> "sound" and therefore there's not much market for a system that
> gets rid of the "custom sound" and gives you more power in exchange.
>
> But today, generally the bolt-on stuff is a waste of money, unless your
> going to completely change the entire setup on the bike - cam, timing,
> intake, carbs, pistons, exhaust - in order to change the performance
> premise the bike was setup on by the factory.
>
> Ted
And all this should go in the book: "What every motorcycle owner should
know".
Rob.
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