Exhaust query

bobber · Post by **bobber** » Thu Dec 10, 2009 10:49 am

Hello, I'm currently building a G5 and am planning to run it using only the exhaust pipe i.e with no silencer. Can anyone tell me if this will adversely affect the performance of the engine,if the jetting in the carb will need to be changed and if there is an optimum length for the exhaust pipe? Thanks and regards, Andy.

GSAX1 · Post by **GSAX1** » Thu Dec 10, 2009 12:04 pm

It will "adversely affect" your neighbours .

But seriously, if you don't know that in most cases the answer to these questions is "yes" then you are in deep water.

bobber · Post by **bobber** » Thu Dec 10, 2009 1:46 pm

I'm building the bike for off road use so shouldn't annoy the neighbours too much! What I really want to know is, what will happen, in terms of performance, if I simply bin the silencer and make no other changes to the standard settings?

GSAX1 · Post by **GSAX1** » Thu Dec 10, 2009 2:27 pm

You could expect that the mixture could be leaner in some rpm ranges. Performance in some rpm range would probably drop. Most piston engines are tuned so that they need a certain amount of backpressure in the exhaust system for best power. The length of the exhaust pipe is also carefully calculated (or determined by testing) to give best power with that particular cam timning and carburation combination. Any change in the exhaust pipe length would probably change the power curve in a unfavourable way.

Michael

bobber · Post by **bobber** » Thu Dec 10, 2009 3:26 pm

Michael, Many thanks, I guessed there would be some impact - I'll need to reconsider or look into it in more detail. Regards, Andy.

rex.webb · Post by **rex.webb** » Thu Dec 10, 2009 10:29 pm

Bet you will not notice any difference??.How can you compare if you have no rolling road ??.
Any one got a Scrambler model still ? they could give you there pipe length and spec .
Ride with Care and Live Long.