Custom Exhaust help 49cc

R

Robert k

Guest
#1
I am designing a motor limo bicycle 49cc
I was thinking adding 2 exhaust together first the expansion tube exhaust in the front then piped down to a poo poo long pipe muffler going down the side.
Was wondering would doing that hurt any performance or anything
 


FNTPuck

Active Member
Joined
Jul 2, 2018
Messages
198
Likes
95
#2
Assuming 49cc 2stroke since you mentioned expansion chambers?

I would instead run the proper tuned exhaust from the header, then just extend the tailpipe outlet with some straight pipe to where you want it. Support it with brackets to the frame so it doesn't vibrate like crazy and crack. If you want to make it flashy you can always add an exhaust tip to it to make it look better.

The exhaust is a sensitive part of a 2stroke bike and the tuned chamber ones are shaped a specific way for that reason, so I imagine adding a second one right after it would wreak havoc on the exhaust pulses and likely negate much of the performance benefits.

Adding or removing length in the header portion before the chamber effects the behavior of the motor, but although I never sat and tested it I don't think adding length after the tuned portion would have any noticeable effect.

*edit* gary55 has tested it, and found that modifying length even it its after the tuned portion it will still change how the motor runs (y)
 
Last edited:

gary55

Well-Known Member
Joined
Nov 27, 2012
Messages
2,792
Likes
745
#3
Adding length after the chamber in my experience will affect the performance along with the heat of the engine. These are before and after pics of my exhaust. The after pic with the muffler directly off the pipe ran leaner. Like FNT I think that putting a poo poo after the chamber ( either the one with a expansion chamber or the one with just the muffler( would be a disaster.
View media item 60844
View media item 61474
 
Last edited:

FNTPuck

Active Member
Joined
Jul 2, 2018
Messages
198
Likes
95
#4
Adding length after the chamber in my experience will affect the performance along with the heat of the engine. These are before and after pics of my exhaust. The after pic with the muffler directly off the pipe ran leaner. Like FNT I think that putting a poo poo after the chamber ( either the one with a expansion chamber or the one with just the muffler( would be a disaster.
View media item 60844
View media item 61474
Awesome testing, thanks for sharing!
 

Top