I didn't do a lot to it. I took the catalyst out of the stock muffler(I thought it was clogged) widened the exhaust,intake port, and matched all the sufaces up, ngk plug and cap. None of this helped top end performance or much in any other performance for that matter. The gearing was always and will always be the limiting factor. I stand corrected on my last post also. You could raise the exhaust port and make the motor run at a higher rpm but you'd lose bottom end and the motor likely wouldn't last very long. I'm still good with 25-30mph40 tooth sounds a little more reasonable, and certainly doable. But you'd likely need to have tuned the engine quite a bit.
no moron, ive only been on this forum for a month or two. and these engines arent that complicated, there actually a joke. try building up a car motor.oh they are faster than you.
6 months ago they posted & you are just starting to catch up.
i was just making fun.try building up a car motor.
39mph with a 44 tooth..Are you sure that isn't KPH??????????????/My stock 66cc with the stock 44 rear will go 39mph(not downhill but probably wind to my back). I have found that once these little engines are hot they will pull 30+ with enough room.
oh and you can get those sprockets from here