Re: How fast will a beach cruiser with 49cc 4 stroke motor go with a 155ib user on it
Stock engine with stock 44T gear on a 26x2.125" wheel, probably just under 30MPH. Every 2-stroke with stock gear I've had (all were 66cc) topped out under 30. The 49cc can rev a little higher tho. For every 1 tooth smaller rear gear, you gain about 1mph.
I ran a 34T on my first motored bicycle which gave it a top speed of ~38mph (could go faster if I wanted to overrev) and a great cruising speed of 28-30. YMMV.