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Old 05-03-2010, 03:34 AM
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BarelyAWake BarelyAWake is offline
Motorized Bicycle Elite Member
Join Date: Jul 2009
Location: Maine
Posts: 7,212
Default Re: Something Good Happened Today

karryhunt - about 200 miles ya say? I'd lay long odds that you've simply reached that wonderful point where yer engine has fully broken in and is finally runnin' right

Now jus' continue to ride the bejabbers outa the thing!

Originally Posted by hambro View Post
I was just wondering how many different variations there are on those stock kit mufflers. I myself have seen about 4 different types and I know for a fact that some are way more restrictive than others. If anyone has any info on this I'd love to know. &

But TBH even if you've the type kit muffler that can be drilled to reduce back pressure, it's a marginal gain at most with the predominant change mostly a placebo effect as louder seems faster. Reducing back pressure is mostly a 4 stroke thing as two strokes need some amount of back pressure to perform properly - reduce it too much and the fuel/air charge can pass right through the combustion chamber before ignition. This is why an expansion chamber exhaust system is so important on a two stroke - it "times" the back pressure into a pulse, essentially making it the exhaust valve we haven't got.

Ofc some kit catalytic mufflers have too much back pressure, to the point where it's far too restrictive - but if you're after a true performance gain, replacement with an expansion chamber is the only real option no matter which kit exhaust you've got.
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