Sprocket and Chain compatibility

[VictorW]

Hello, I am in the process of building a small moped, the frame almost completed and the engine in place, my question is about using a 49cc 2 stroke chinese bicycle engine and a sprocket on the wheel.

What chain is compatible with stock chinese 49cc and ANSI 40 16 tooth sprocket.

Picture for reference

 

[anickode]

If the sprockets have a different pitch, no chain will be compatible with both.

A drawing really does us no good without knowing the pitch of the engine sprocket.

 

[Brianator]

40 chain on a 49cc? Is it 2 or 4 stroke? The little 49cc 2 strokes generally use 25h chain and the larger 4 strokes (e22 or "monkey" motors) found on small quads, mini choppers ect. generslly use 420 which is the same 1/2" pitch as 40 but too thin to fit a 40 sprocket.... 428 is also 1/2" pitch and a little wider than 420. Problem is roller diameters also vary so you need to know exactly what you have before you proceed.

 

[VictorW]

The engine sprocket pitch seems to be 1,27cm (1/2in)

A ansi 40 sprocket would work?

 

[Brianator]

If it is a standard 40 then yes, 425 sprockets and chain are also fully compatible. I'd actually like to thank you for bringing this up as you've reminded me to do a little research, I've been wanting to find out what chain will work with my 40 sprocket but is better than standard 40 chain, the answer is 425. Problem is it's hard to find...

Post #4 in this link I'm posting has 2 good links that will explain everything you need to know AND it's from this forum so you know it's safe!

http://www.diygokarts.com/vb/showthread.php?t=10135

*edit* I just realized I asked a question you already gave the info for (it's a 2 stroke) BUT that leaves a couple questions... what tire size and rear sprocket are you using? With a 16 tooth front sprocket you could run into issues with burning up clutches/belts which brings me to my next question, does this motor have a gear reduction or cvt?

 

[VictorW]

Wow thanks for the indepth info, I was scratching my head looking at pitch, roll and trying to figure out if compatible.

6 inch tire, 10 tooth engine sprocket, 16 rear, it has 20/82 reduction, so if my math is right 16 rear seems reasonable for 14 mph at 75% throttle. 5k rpm

My design

 

[mckutzy]

What is the motor you are using??

 

[VictorW]

mckutzy, 49cc 2 stroke chinese bought 2011

 

[Brianator]

Np and it sounds like you've done your homework! Looks like a neat little scooter, keep us updated as you go along or feel free to start a build thread in one of the other build sections!

 

[txluke]

Here is a chart.