49cc razor scooter

kidgambit

Active Member
#1
I am in the middle of putting a pocket bike engine into a razor vespa thing. But a guy on YouTube did this. And says the thing is slow because of the massive rear sprocket. I need help figuring out the right rear sprocket. The razor has a 12 inch wheel
 

MikeBear

Active Member
#2
Put the massive sprocket on the engine, and the small engine sprocket on the wheel. Easy, and if you can get it to move with you on it, it'll go like Hell! lol

Anyway, you want around 1:6 (up to 1:9) or so ratio for good all-around speed versus power. So, if the engine sprocket is say 1 inch, the wheel sprocket would be 6 inches.

You'll probably need a jackshaft setup, so it might be a little more complicated. However that ratio should be your final drive ratio.
 

MikeBear

Active Member
#5
The amount of teeth doesn't matter. That depends on what size chain you are going to use. All that truly matters is the physical size of the drive sprocket, versus the size of the rear sprocket. You want the above 1:6 up to 1:9 ratio range I quoted. Whatever is easiest for you to find for use.
 
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