Fantastic little engine.
Used one of these on a small wooden go kart project, and I couldn't be happier with it.
It came with a 14t sprocket, which I paired with a 32t rear sprocket on 14" tires. This combination seems pretty balanced and tops out around 45mph. The electric start is great and wiring wasn't too difficult overall.
There is plenty of helpful documentation available online.
Don't forget to buy an exhaust system and an air filter.
It's pretty sensitive to stale gasoline, so if you have difficulty idling without using the choke, check your fuel.