With the 44-tooth sprocket that comes with the kit on a 26-inch bicycle wheel the little engines top speed at the RPM red line is 32 MPH, which is way too fast on a bicycle! I normally keep my speed between 20 and 25 MPH. Note the additional front brake along with the coaster brake. Doing this is an absolute must! A coaster brake alone will get you killed. These Chinese bicycle engines kits are made to fit on Chinese Flying Pigeon bicycles, which have 28-inch wheels and will do 40 MPH with a 44-tooth sprocket. The Chinese use 50-tooth sprockets on bicycles with 28-inch wheels. I've seen a 36-tooth sprocket used on an old road bike with 27-inch wheels. The insane rider had to get the bike up to 15 MPH before letting out the engine clutch to prevent lugging the engine and top speed was around 50 MPH.

If I keep my speed down around 15 MPH and keep to flat roads I can get 70 miles on 2-liters of mixed 20:1 ratio gasoline. I typically get about 40 miles per 2-liter tank full running around town which includes climbing steep hills.