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I have done 60mph on my 66cc ZL Rod motor Stock head shaved, Piston skirt trimmed for intake and top ramped for exhaust.
Boost bottle.
Aftermarket CDI from Gasbike,
26 tooth rear sprocket
Stock pipe modded for free flowing exhaust.
That must be some joy to ride :rolleyes:
 
Ive gotten my bike up to 58mph on flat ground and have been clocked several times at 63-65 mph going down hill. i have also been stopped for doing 45 in a 30mph zone.
 
My bike build goes 45mph with no shifting kit!

This is what I have purchased:

1. 66/80cc Flying Horse Silver Angle Fire Bicycle Engine Kit-bikeberry
2. BBR Tuning Silver Boost Bottle Induction Kit-bikeberry
3. BBR Tuning Boost Intake Manifold (30mm)-bikeberry
4. Pull Start Assembly-bikeberry
5. BBR Tuning Torque Up Exhaust Pipe Muffler-bikeberyy
6. UNI Flex Carburetor Air Filter-bikeberry
7. Uni Filter UFM-400 Filter Oil and Cleaner Service Kit
8.High Performance Muffler Gasket-GXParts (need for when I bought my new muffler)
9. BBR Tuning Billet Carburetor Racing Velocity Stack
10. 80cc Motor bicycle Gas Engine 28 Teeth flat sprocket-ebay
 
Ive gotten my bike up to 58mph on flat ground and have been clocked several times at 63-65 mph going down hill. i have also been stopped for doing 45 in a 30mph zone.
Hows it do going up hill?
 
Ive gotten my bike up to 58mph on flat ground and have been clocked several times at 63-65 mph going down hill. i have also been stopped for doing 45 in a 30mph zone.
Show us some pics. of this screamer.
 
Yes, think of a large wheel versus a small wheel at the same rpm, because of the larger circumference the bigger wheel is going to travel faster forward at the same rpms. Also means you don't need to spin the wheels as fast to get the same speed than what would be seen on the small wheels.

Logically speaking if the sprocket is larger on the wheel then the speed will be faster at the same engine rpm just like how the wheels work on flat ground. You probably have to imagine the chain as being the flat ground since it's the only flat part touching the sprocket.

If you notice that adding a larger sprocket made you slower then you probably messed up somewhere but it might be fixed by using a smaller rear wheel to offset the change in sprocket diameter.
 
If the sprocket is larger the wheel speed is less at the same rpm! A larger sprocket may allow a engine to unload to higher rpm witch could = more mph!
 
I'm thinking a stock engine won't have the power to allow the 28 tooth sprocket to reach it's potential. Just to much resistance, so a larger sprocket could in this case provide more speed by allowing the engine to pull it. If you soup the engine up to have enough torque to pull the 28 tooth, better hold on to your hat. It's all about finding the sweet spot between rpm, torque, and gearing to suit your needs.
 
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