Thread: Silence my bike
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Old 05-25-2010, 05:06 AM
BarelyAWake's Avatar
BarelyAWake BarelyAWake is offline
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Join Date: Jul 2009
Location: Maine
Posts: 7,212
Default Re: Silence my bike

Cabinfever has some good suggestions!

I like a quiet bike if for no other reason than so I can hear myself think lol

It's true that many like the screaming death noises - equating decibels with speed, it amazes me how many will stick a supertrapp on the back of their Ford Escort - Mario Andretti in an economy car right?

Still, to each their own and it's also true that in the quest for top performance often mufflers are the first to get sacrificed. With good reason, most mufflers are insanely restrictive, much like trying to run a marathon breathing through a drinking straw. Drilling holes & pulling endcaps seems to help, but with two strokes it really doesn't, not as much as it seems anyway - it's mostly a placebo effect as a screaming engine has just got to be fast lol Unfortunately, just sticking an additional muffler on the end of your exhaust will make that drinking straw even smaller.

One easy way to reduce exhaust noise is to simply increase the length of the exhaust system. While length does increase back pressure, it's marginal and well worth it if you're after quiet. Not only does it help reduce the noise - it puts it behind you where it's far less annoying... for the rider anyway heh, a simple solution would be the "poo-poo" pipe sold by some of our vendors... but it still has the stock muffler on it and the generic (if longer) headpipe..

Two strokes need some back pressure to run properly, they need tuned back pressure for performance - problem is most expansion chambers go with the "louder must be better" theory and that can get annoying - but easily fixed. Of the available expansion chambers most don't have any silencing at all, but some do and the best for performance and noise reduction both have a glasspack silencer on the end.

As you can see from the pic, there's no baffles, no screens or plates - the exhaust can freely flow through the inner pipe as the fiberglass sound insulation absorbs some of the shock wave, deadening the "bang" much like a gun silencer. The only downside is the fiberglass batting will load up with carbon and unburned oil in time, needing to be repacked periodically. Not really a big problem though as regular old household insulation fiberglass will do just fine and it's usually only four pop-rivets or screws to get it apart.

I took the SBP's expansion chamber exhaust and doubled the length of it's glasspack silencer, it's now just a little quieter than stock at half throttle or less - it wakes up and gets louder only at WOT, which is exactly how I like it lol;

It would help to reduce the noise even more (and even maybe a tiny bit more power) if I wrapped the headpipe and chamber with Header Wrap... but I've not gotten to that yet lol, it's on the "to do" list tho heh

As Cabinfever mentioned, another way to help reduce noise is the oft-forgotten intake end, for more ranting about that - check this thread:

Last edited by BarelyAWake; 05-25-2010 at 05:11 AM.
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