Exhaust Question

[FrizzleFried]

Thus far I've seen only 3 different "purpose built" bicycle motor exhausts... one thing that all 3 shares was the same size "round" opening that gets mounted to the motor.

I am not sure about all motors, but I can say for sure that MY motor does NOT have a "round" exhaust port... being more wide than tall.

Are there any purpose-built bike exhausts that properly mate up to these wider ports? I can only imagine there is some performance to be gained there... no?

 

[michael whiteman]

First of all............what type motor are we talking about...........and do you have a picture?

 

[Chainlube]

Thus far I've seen only 3 different "purpose built" bicycle motor exhausts... one thing that all 3 shares was the same size "round" opening that gets mounted to the motor.

I am not sure about all motors, but I can say for sure that MY motor does NOT have a "round" exhaust port... being more wide than tall.

Are there any purpose-built bike exhausts that properly mate up to these wider ports? I can only imagine there is some performance to be gained there... no?

The answer to your querie is YES, but, you can't buy them on the internet, or anywhere for that matter. You have to make them, then they're purpose built.

 

[FrizzleFried]

Do you think adding a small exhaust manifold that smoothly transitions from the larger wide opening to the smaller round opening would make any kind of difference?

 

[michael whiteman]

Again ! What engine do you have ? 2 or 4 cycle ? What are the inside diameters of each ? Yes, technically it would make a little difference. Whether it would be noticeable or not is the question.

 

[FrizzleFried]

My apologies... 2-cycle standard ole PK80 I do believe it is (I got it from Heli•io Bikes).

(Is that what it is?)

 

[michael whiteman]

You can get into a never ending discussion on back pressure with 2 cycle engines. I'm a 4 stroke guy so I'm out. I'm sure you'll see a lot of opinions now. It all comes down to how much do you want to spend for a performance exhaust verses the HP gain or just the "cool" factor.

 

[Chainlube]

Do you think adding a small exhaust manifold that smoothly transitions from the larger wide opening to the smaller round opening would make any kind of difference?

The best thing would be to place the muffler in the position on the bike that you want, maybe up beside the engine or down under the bottom bracket. Put it on or near the position you want backward, tape it or wire it in place and bend a piece of 1" or 25.4mm tube to reach the pipe. Cut the pipe off where it's 1", flare it out until the new header fits in and weld 'er up. You probably can reuse the old flange from the other end.