Originally Posted by Tim_B_172
Wow, I kinda forgot about this thread. Well, the 56t sprocket bike that I put together actually worked quite well. We were seeing speeds of about 25mph on flat ground, and it climbed hills without braking a sweat. That bike is currently grounded pending some major engine work. It has a very nasty vibration (like rattle you're fillings out NASTY) at the top end which I think is caused by improper installation of the crankshaft weights.
It's an older engine and it always had that problem which is why Dad stopped using it to begin with, so there's no chance of exchanging it.
If there's no hope of exchanging the engine on your Dad's bike ,there is an excellent sale of replacement engines from Zoom....$59.95 for a 49cc motor and $69.95 for the 80cc motor.....here's the site....I use Zoom kits exclusively and have never had an issue other than a bad carb once....they use a much larger intake pipe and port also....makes a big difference....
Zoombicycles **BLOWOUT SALE** Replacement Engines | EHBC Distributors Ltd
Hope this helps,