How do I gut my standard muffler with end cap? Told this is louder but more rpm's? Would extending pipe to muffler help?
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Muffler
- Thread starter Flathead
- Start date
Flathead, the worst thing we can do to this sport is make a lot of noise and gets us blacklisted and outlawed by the public we offend. Speed and noise will do that. I like speed but know I need to be careful with it. I pedal the bike at all times so as not to flaunt that I am powered and I have a quiet muffler. I shut the engine off in town and around pedestrians. It is important you and other M-bikers keep the engine quiet if you don't want to be banned.
Experiment. I found a private roadway where I could test the muffler and ran it cap on, cap off to test for speed and power up a hill. It sounded more powerful with cap off, but the GPS told the story of almost the same speed and less on the hill without the cap. This chrome Grubee muffler works well.
The black Grubee muffler is not as quiet or as powerful (but it is EPA compliant!) and it was faster with the cap off. A quick look shows the difference in construction. The chrome pipe has main straight flow pipe to the end with side baffle chambers and a small "stinger" tube going up to its center. Very much like a resonant pipe and/or Turbo muffler. The black pipe had no center tube but has to flow back and forth over the baffles to get to the end. The stinger is short and at the end only. Poor design and would only work better with the baffles gone. Its going to be nasty noisy like that.
So, if you cannot buy the $19.99 chrome Grubee pipe, what can you do to get power and quiet?
Make your own I guess. I have not done it for this bike, but I have for motocross and enduro bikes. I have a ton of experience with them. A resonant pipe is the answer and most of all a small stinger out of the CENTER of the pipe's belly. It is much quieter from there. You can even add a muffler to it after that.
So why not take the cap off or drill out the stinger to get more exhaust out of the pipe?
Look at the this animated gif very carefully. Notice this tuned pipe pushes the exhaust gasses back into the cylinder at the last moment? It takes resonant waves AND back pressure to accomplish this. The "stinger" is sized just perfect to pump mixture back into the cylinder at the last moment. It has the rest of the cycle to exit the pipe. Bigger is not always better.
Steve
Experiment. I found a private roadway where I could test the muffler and ran it cap on, cap off to test for speed and power up a hill. It sounded more powerful with cap off, but the GPS told the story of almost the same speed and less on the hill without the cap. This chrome Grubee muffler works well.
The black Grubee muffler is not as quiet or as powerful (but it is EPA compliant!) and it was faster with the cap off. A quick look shows the difference in construction. The chrome pipe has main straight flow pipe to the end with side baffle chambers and a small "stinger" tube going up to its center. Very much like a resonant pipe and/or Turbo muffler. The black pipe had no center tube but has to flow back and forth over the baffles to get to the end. The stinger is short and at the end only. Poor design and would only work better with the baffles gone. Its going to be nasty noisy like that.
So, if you cannot buy the $19.99 chrome Grubee pipe, what can you do to get power and quiet?
Make your own I guess. I have not done it for this bike, but I have for motocross and enduro bikes. I have a ton of experience with them. A resonant pipe is the answer and most of all a small stinger out of the CENTER of the pipe's belly. It is much quieter from there. You can even add a muffler to it after that.
So why not take the cap off or drill out the stinger to get more exhaust out of the pipe?
Look at the this animated gif very carefully. Notice this tuned pipe pushes the exhaust gasses back into the cylinder at the last moment? It takes resonant waves AND back pressure to accomplish this. The "stinger" is sized just perfect to pump mixture back into the cylinder at the last moment. It has the rest of the cycle to exit the pipe. Bigger is not always better.
Steve
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Thank you, Steve. That is as good an answer as has ever been posted here.
Speed and power are always going to be the focus of a certain segment of the motorized bicycle community. However we are living on the edge as far as legislation is concerned and excess noise is just more ammunition for those who would see our hobby banned.
It is a bicycle. Not a motorcycle, not an off-road trail or dirt bike and the majority get ridden on city streets and in neighborhoods where noise will get noticed and acted on.
All of my bikes are capable of speeds in the high 30s and low 40s. But, they're quiet. I see no reason for loud exhaust that will only bring unwanted attention to our bikes. There are other ways, as you've pointed out, to achieve a little more power. Removing the end cap, which offers mostly a placebo effect, is the least advantageous.
Tom
Speed and power are always going to be the focus of a certain segment of the motorized bicycle community. However we are living on the edge as far as legislation is concerned and excess noise is just more ammunition for those who would see our hobby banned.
It is a bicycle. Not a motorcycle, not an off-road trail or dirt bike and the majority get ridden on city streets and in neighborhoods where noise will get noticed and acted on.
All of my bikes are capable of speeds in the high 30s and low 40s. But, they're quiet. I see no reason for loud exhaust that will only bring unwanted attention to our bikes. There are other ways, as you've pointed out, to achieve a little more power. Removing the end cap, which offers mostly a placebo effect, is the least advantageous.
Tom
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