Quietest muffler?

[Andrew1234]

Was wondering just how quiet you could possibly make one of these bikes and how restrictive it would be to do so.

 

[darwin]

Jeez I'm flabbergasted. Someone who likes quiet, only 2 of exist and I'm not alone.

 

[ImpulseRocket]

2 stroke or 4 stroke?

I am assuming two stroke. The stock muffler is about the best you will get if you want the quietest. A packed chambered muffler is the king of quiet. The nature of how 2 strokes run combined with the loose tolerances of the cheap little 2 stroke motors, and the short basically open throat intake system = noisy.

 

[toojung2die]

If you put a quiet muffler on these two-strokes you are going to be surprised how much noise is coming from the intake. I made a long exhaust pipe from EMT conduit and put the stock muffler by the rear axle. It made the exhaust much quieter and I could barely hear it while riding. Now I heard how loud the intake was. The overall amount of sound coming from the engine was barely reduced.

 

[GW's Motorized]

You can get a 4 stroke pretty quite

 

[robe]

If you put a quiet muffler on these two-strokes you are going to be surprised how much noise is coming from the intake. I made a long exhaust pipe from EMT conduit and put the stock muffler by the rear axle. It made the exhaust much quieter and I could barely hear it while riding. Now I heard how loud the intake was. The overall amount of sound coming from the engine was barely reduced.

I want to make an air box to quiet down the intake but haven't got to it yet.

I have one of the aftermarket glass pack mufflers on the end of my clone expansion chamber. This works really well in quieting the exhaust.

As you said the next loudest thing is the intake followed by the ringing of the cylinder itself and the sound of the primary gears.
Some wrap the exhaust, put high heat silicon spacers between the fins and glue a piece of cork to the primary cover.

I was thinking of a PVC elbow to under the seat with a baffle or two in it. Easier said than done with the space restrictions.

 

[DAMIEN1307]

Jeez I'm flabbergasted. Someone who likes quiet, only 2 of exist and I'm not alone.

Your not the only one Darwin...lol...If there was a way to make mine totally quiet, I would...lol...When I was young, I liked all the noise in the world from a good engine.

Not so much now as I am getting a little more "mature"...lol.

 

[Wyvern]

Part of the issue with 2 strokes is how they operate, no valves mean when ports are exposed, especially the exhaust, you get a "pop".

The best I've found is a looong gas-packed muffler and believe it or not, a rubber tip pointed towards the ground.

My Avenger is not quiet, but it's also not that loud and very mellow sounding compared to a lot of these engines. It's because it comes with a big fat glass pack pointed straight to the ground.

 

[ImpulseRocket]

I imagine the avenger is about the same loudness as the Phantom. People think the phantom is louder than a standard 2 stroke exhaust, but in terms of dB level it's about the same. It seems louder because the larger exit pipe means a larger volume of air is "popping" out the end which gives a perceived loudness.

Glass packing on it's own only muffles gas flow equivalent to a specific atmospheric pressure relative to it's internal packing dead space volume. This is why straight through mufflers are quieter at idle and low rpm and throttle position, but almost as loud as a straight pipe when you open it up all the way.

Chambered mufflers don't flow as good when pushed but are more effective at sound wave cancelation since they use baffles for the sound waves to bounce off of. These mufflers tend to have a metallic and almost hollow sound to them - aka EVERY 5.0L Mustang from my younger days.

Chambered mufflers with glass packed chamber spaces are the best at completely damping sound. They can have larger chambers with less changes in flow direction so they can co.promise between flow and noise level. Think Bassani mufflers and some models.of Borla.

The stock exhausts are Chambered and glass packed. Why they actually do such a good.job in such a small package.

 

[Wyvern]

I imagine the avenger is about the same loudness as the Phantom. People think the phantom is louder than a standard 2 stroke exhaust, but in terms of dB level it's about the same. It seems louder because the larger exit pipe means a larger volume of air is "popping" out the end which gives a perceived loudness.

Glass packing on it's own only muffles gas flow equivalent to a specific atmospheric pressure relative to it's internal packing dead space volume. This is why straight through mufflers are quieter at idle and low rpm and throttle position, but almost as loud as a straight pipe when you open it up all the way.

Chambered mufflers don't flow as good when pushed but are more effective at sound wave cancelation since they use baffles for the sound waves to bounce off of. These mufflers tend to have a metallic and almost hollow sound to them - aka EVERY 5.0L Mustang from my younger days.

Chambered mufflers with glass packed chamber spaces are the best at completely damping sound. They can have larger chambers with less changes in flow direction so they can co.promise between flow and noise level. Think Bassani mufflers and some models.of Borla.

The stock exhausts are Chambered and glass packed. Why they actually do such a good.job in such a small package.

Listen to clips of the two engines back to back, there is definitely something a little different about the avenger, it's definitely got a mellower muffled sound to it especially at idle, really fun.

But it's still very loud at full crack.