Compatibility question of Chain and Sprocket

[VictorW]

Hello, I'm building a simple ''moped'' and using a 49cc 2 stroke chinese bicycle engine. My question is about using the stock sprocket on the engine and a ANSI 40 sprocket for the wheel, don't have the chain yet, what chain will be compatible with 16 tooth ANSI 40 Sprocket?

 

[Greg58]

Your rear sprocket needs to be 36-40 tooth 1/2 pitch, the Chinese 2-stroke has a internal gear reduction that's 6/1 I believe.

 

[VictorW]

But the wheel size is 6 inches, there is no available motorized rear sprocket 20 tooth or lower, so I have to use other type of sprocket

 

[Greg58]

You’ll have to give it a try to see how it does, with that small of a tire it may pull ok. The 415 chain and the 40 chain are the same pitch just the 40 is wider. The problem may be the 40 hitting the housing or chain cover on the engine. If you have a local machine shop they can mill the rear sprocket to fit the engine chain.