Exhuast for a 50 to 10cc 139qmb
 

How important is it to replace the exhaust with a ""performance" exhaust afyer the 100cc upgrade?
As well, via ebay. What would be a good pick for one?

Other things ive done
20mm carb, cdi box and cable, 9g slider (seeing what hapens after install) 1500 rpm clutch/kontra spring, open element filter. Dunno what jet is in the carb as of now.
Will need advice on carb adjusting later after new parts are in.

A standard Chinese made BBK 100 (83cc) upgrade does not need a bigger carb or performance exhaust. In those areas, all it needs is a properly jetted oem carb.

The so called performance CDI modules (blue & orange) and ignition coils are a waste of money and those CDIs can cause damages from over advancing timing at crank time.

Too heavy of Engine Variator rollers will cause belt engagement at idle and can cause clutch and belt failure if the driver has to hold it back when stopped @ traffic lights.

I was thinking of undoing changes andsee how it ran stock. Its been running slow since. After thw 100cc upgrade it ran very well. Glad parts arent exensiv thhough. Been a good learning experiance :)