Wolfshoes
Member
If quieting the china girl is a performance mod, then this thread is in the right place. A second stock chrome type about $20 exhaust from ebay vendor rose326a was added to their mighty 66cc Grubee GT5 engine in series, not as a dual exhaust. As much as I would like more power, I would like even more for the motorbike to be quieter. This was achieved by using all stock pieces from a local Menards.
![100_1801[1].JPG](https://motoredbikes.com/attachments/100_1801-1-jpg.78147/ "100_1801[1].JPG")
![100_1802[1].JPG](https://motoredbikes.com/attachments/100_1802-1-jpg.78148/ "100_1802[1].JPG")
![100_1804[1].JPG](https://motoredbikes.com/attachments/100_1804-1-jpg.78149/ "100_1804[1].JPG")
If the stock muffler removes half the noise, adding a second muffler seems to remove half of the remaining noise. I am somewhat surprised to mention that have not noticed a drop in power, even riding up hill. The second muffler is installed inverted with the exhaust exiting to the side from a copper elbow. I expected this arrangement to be temporary, but exhausting to the side has not been noticeable when riding. I have been using 100 to 1 Opti-2 lubricant and there is no noticeable smoke. The lower fittings are stock 1/2" copper tube (as a bushing, thinner red label type) followed by a 1/2 to 3/4 elbow, followed by a street 3/4 elbow. The final exhaust is 1/2" copper tube (as a bushing) followed by a 1/2" elbow. A street 1/2" elbow would be better. The parts are not soldered together to resist vibration problems.
I am happy enough with the results to use this setup permanently.
In dinking around with exhaust in the past, a one way flap was made part of a silencer. At low RPMs it was apparent that the final exhaust was a two way street with air entering the exhaust pipe. This could be speculated as necessary for exhaust to reenter the motor. It further could be speculated that as a off setting benefit, the added set of muffler baffles resisted the backwards flow into the motor. This expansion chamber like effect could explain why there was no noticeable loss in performance using a second muffler on the two stroke.
If the stock muffler removes half the noise, adding a second muffler seems to remove half of the remaining noise. I am somewhat surprised to mention that have not noticed a drop in power, even riding up hill. The second muffler is installed inverted with the exhaust exiting to the side from a copper elbow. I expected this arrangement to be temporary, but exhausting to the side has not been noticeable when riding. I have been using 100 to 1 Opti-2 lubricant and there is no noticeable smoke. The lower fittings are stock 1/2" copper tube (as a bushing, thinner red label type) followed by a 1/2 to 3/4 elbow, followed by a street 3/4 elbow. The final exhaust is 1/2" copper tube (as a bushing) followed by a 1/2" elbow. A street 1/2" elbow would be better. The parts are not soldered together to resist vibration problems.
I am happy enough with the results to use this setup permanently.
In dinking around with exhaust in the past, a one way flap was made part of a silencer. At low RPMs it was apparent that the final exhaust was a two way street with air entering the exhaust pipe. This could be speculated as necessary for exhaust to reenter the motor. It further could be speculated that as a off setting benefit, the added set of muffler baffles resisted the backwards flow into the motor. This expansion chamber like effect could explain why there was no noticeable loss in performance using a second muffler on the two stroke.
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