Silence at no cost?

[Jayjohnson]

Is it possible to keep the engine running quietly without necessarily restricting exhaust flow and hindering performance. Also wondering if I have a fram that takes 4 inch wheels, is it possible to put 2inch wheels on. I tried and it ruined the axel by bending the s**t out of it

 

[ImpulseRocket]

Is it possible to keep the engine running quietly without necessarily restricting exhaust flow and hindering performance.

Possible, yes. Practical? probably not but it depends on how quiet/loud we are talking. With the limited space on a bike, you end up making compromises. A straight through packed muffler will offer the best flow, and if large enough can also do a good job of keeping noise down, but if you want Prius levels of quiet, it won't ever achieve it. A chambered style muffler turns the sound waves against themselves and is much more effective at noise cancellation, especially in a small area, but also restricts flow a lot more and potentially hindering performance. The ultimate combination of the two is a straight through muffler with a helmholtz resonator placed somewhere before it to cancel out the most prominent frequency of the system.

You would be surprised at how much time goes into engineering exhaust systems for vehicles in order to get the best balance of meeting noise regulations, sounding good, and fitting within the confines of a vehicle. A large part of that effort is put into resonance wave tuning (aka, the Helmholtz resonator, among other things).

On my Jeep Comanche I had a set of long tube headers, a crossover pipe to the passenger side, and the largest magnaflow muffler I could get my hands on at the time, which was a 2.5" in and out with a 28 inch body basically taking up the space where the catalytic converter used to be all the way back to where the muffler used to be, and a turndown right before the rear wheel. That giant muffler was amazingly quiet, but made just the right amount of noise when the pedal was pushed down to sound good.

 

[Chainlube]

Is it possible to keep the engine running quietly without necessarily restricting exhaust flow and hindering performance. Also wondering if I have a fram that takes 4 inch wheels, is it possible to put 2inch wheels on. I tried and it ruined the axel by bending the s**t out of it

Make or buy a glass pack muffler for the end of your exhaust. I made one for this bike. When I rebuilt the stinger, I drilled a few dozen holes through the inner pipe. Welded a second pipe over it,(old CG muffler cut down), stuffed it full of insulation and capped it off.

 

[robe]

The field of sound reduction is like any other field of engineering. Once you know a bit you quickly realise how vast and deep these things go.
Modern MC's have managed to achieve a high level of sound reduction through a number of improvements. Sound cancelling exhaust, liquid cooling and sound cancelling intake to name a few.

Once you quiet the exhaust, the intake, the gears, wrap the pipe, you still have the air cooled cylinder ringing like mad. There are silicon inserts for between the fins that help a lot. That's about it. Much quieter yes, silent never.

One of these days I would like to really work on quieting mine down but haven't done much yet. In the thread, My bike almost dialled in, I made a easy mod to the stock muffler I am happy with.