chain keeps coming off when starting.

[the_edge150]

ok i got a new happy-time 50CC kit, built it (took 3 days) and now every time i go to start it, the chain comes off the drive sprocket. any ideas??

 

[ebmvegan]

Check to see if the chain rolls onto the sprocket easily. The pitch or roller diameter or with could be off. Or the drive sprocket and wheel sprocket could be misaligned. Also check the tension of the chain.

 

[Bikeguy Joe]

Too much tension.
The roller/tensioner is out of alignment (sometimes you have to twist the metal a bit if your chainstays are angled.)
Engine out of alignment with rear sprocket.

 

[the_edge150]

i loosened it up and its working a bit better,and i mounted the tensioner onto the plate where the coaster brake arm goes, so its riding pfine now, thanks for helping