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Attaching a motor to a bike? Answered

I have an old motor that I'd like to attach to a bike. There are a few things that concern me though that I was hoping some people could clear up for me:
1. I'm wondering if maybe the motor is a bit too powerful for a bike. The motor is a briggs and stratton 4-stroke 3 horsepower 127cc engine that runs at 3600 rpm. It originally came from an old edger. I've read of people fitting bikes with 70cc engines, but nothing this powerful. If it is too powerful, is there any way to rectify that problem?
2. As I see it, there are 2 ways the engine could be attached: by friction to the tires, either front or back, or by chain directly to the front gears.  Ideally, I'd like it attached via chain in this way creating a gearshifting system from the already existent gears on the bike. But can a bike's deraileur handle the power that an engine brings, or would it be too much?
3. Lastly, I plan on using a centrifugal clutch. However, I've had bad experiences with them in the past that made startup of the engines difficult. (mainly due to the fact that the clutch kept engaging even though the engine was off. You could see how during startup of a go-kart, this could be frustrating.) Do you think a new and properly selected clutch would behave that way?

Thanks a ton in advance! 


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Best Answer 8 years ago

A 127 cc briggs and stratton is half as powerful as most other motors. They are purposefully detuned to last a long time. And they are usually flatheads that don't develeope as much power as over head valves or cam.

2 the chain drive on the bike is probably not strong enough to carry the power.

3 A new properly sized cent. clutch should release even at idle.

Friction drive is probably the best way but your tire and wheel should be wide and strong.

A bicycle wasn't meant to carry a motor so unless you have one of the old bikes made with big steel tubing don't expect it to last for long or be safe/

Either way, wear a helmet.


8 years ago

Test to see if the engine will start and run well vertically. The carb may not be able to handle it.