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Author Topic: Exhaust back pressure  (Read 873 times)

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Offline Hush

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Exhaust back pressure
« on: July 30, 2010, 11:27:45 AM »
My partners bike is a 4 stroke twin (DOHC) and the mufflers are aftermarket ones.
They don't fit too well so there is a fair bit of exhaust loss at the join where they slip on.
My question is, is there any benefit to me improving that seal?
NZ road worthy certificates don't seem to worry if the exhausts leak so I'd only be doing this for some sort of engine improvement.
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline bryanj

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Re: Exhaust back pressure
« Reply #1 on: July 30, 2010, 11:01:23 PM »
Hush, some bikes need a good seal or they will run weak, RD250LC for example---I know thats a 2 stroke but the principle is the same, also if the back pressure is correct it creates a negative pressure wave at the exhaust valve just as it opens to help scavange the gases---complicated but true and one reason why the jap bikes run best with the computer designed original systems.

All in all it may not make any difference but its worth trying to do if only to keep the soot marks off the pink paint
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Offline Hush

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Re: Exhaust back pressure
« Reply #2 on: July 31, 2010, 12:53:26 AM »
Cheers for that Bryan, I respect your opinion on all things motorcycle. :)
I had many two stroke bikes and backpressure was vital to their good running but the Jaffa's GSX400 seems to run quite well with all the exhaust leaks it has, that being said I shall now find a sealer and fix them, you never know it may go even better. ;)
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I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!
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