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Hi guys, I'm working on the pocketbike exhaust mod, and I was wondering if any of you know if its best to have open air flow (Wide-open exhaust) or if there needs to be some form of compression involved at all (like with an expansion chamber). If so, please let me know! Thanks
 

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Hi guys, I'm working on the pocketbike exhaust mod, and I was wondering if any of you know if its best to have open air flow (Wide-open exhaust) or if there needs to be some form of compression involved at all (like with an expansion chamber). If so, please let me know! Thanks
Two Strokes work better with an expansion chamber but can run with a box Muffler.
 

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Best exhaust is the one that you calculated for your Porting. You can calculate the expansion chamber to a targeted power / rpm, then it will work good in a range of +/- 2000rpm of your target. For what engine do you need a exhaust?
You will lose a lot power if there is no expansion chamber on your 2 stroke.
 

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Discussion Starter #7
Best exhaust is the one that you calculated for your Porting. You can calculate the expansion chamber to a targeted power / rpm, then it will work good in a range of +/- 2000rpm of your target. For what engine do you need a exhaust?
You will lose a lot power if there is no expansion chamber on your 2 stroke.
I am making the pipe for the generic 49cc pocketbike engine. I heard from a former member (CAT2) that the pocketbike basically needed as much open airflow as possible. I was thinking of using a bit of short conduit flexible steel tubing to get around some of my mods...
 

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Anything with an expansion chamber for 40cc to 80cc will work good including China girl pipes.

A straight pipe will work but not having an expansion chamber means no power at high RPMs

Open or horn style exhaust will make the engine go lean ( max power ) but quickly burns a hole through the top of the piston

The absolute best for The CAG engine is the stock CAG pipe with 3 inches added to the belly and 1 in of pipe removed from the j bend
 
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