Re: ?Recommendations for HF 90cc Engine Kit
The clutch has an 11T, then -> 22T (2:1). So with say, a 56T sprocket and 26" wheel, you get a 12.44:1 overall, or ~34.5MPH @ 5500RPM
You can swap out that 22T to something bigger (it takes #35 chain) for more reduction and takeoff or use a smaller rear sprocket for higher top speed.
If you set your gear ratio too tall, you'll get some chatter off the line tho. 30MPH should be enough, unless you're greedy IMO lol