Bike won't run

Octo Ro

New Member
May 1, 2019
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I have a motorized bike with a stock engine. Found a bike online with a big ass exhaust, Reed valve, the red speed card, and it's ported. I switched out the body part(the middle section with the ports) between the two bikes so now the stock one is on the bike I bought. It still has the speed carb on it and a windowed piston, but now has stock exhuaust. I don't know why, but when I give it throttle, it like won't do anything. It idles fine and the throttle works then, but when the clutch is out I like don't really go anywhere. Like it sounds bubly or something. It worked completely fine before I switched the body Btw. Any ideas of the problem?
 

FOG

Well-Known Member
Mar 3, 2019
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Motor mods need to be balanced so they can work together. The porting and big exhaust would have a tendency to lean out your motor by increasing air flow, which means the speed carb is probably jetted for those conditions. What you are describing sounds like a motor that's way too rich. You more than likely need a smaller jet in the carb to match the stock porting and pipe.

My best guess anyway and good luck on it.
 

Octo Ro

New Member
May 1, 2019
13
2
3
19
Motor mods need to be balanced so they can work together. The porting and big exhaust would have a tendency to lean out your motor by increasing air flow, which means the speed carb is probably jetted for those conditions. What you are describing sounds like a motor that's way too rich. You more than likely need a smaller jet in the carb to match the stock porting and pipe.

My best guess anyway and good luck on it.
Alright thanks. U think I should swap out the windowed piston too for stock or no?
 

FOG

Well-Known Member
Mar 3, 2019
282
609
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68
The windowed piston is something your reed valve needs to function at full potential. Piston port motors don't have a window because the piston itself opens and closes the intake port. The reed valve does that job in a reed motor so a window is needed to more or less get the piston out of the way.