Help me with my potential build.

B

Burninrock24

New Member
I am planning on assembling my own "kit" if you will, thats why I am posting here. I plan on using the 99cc motor from harbor freight on my 21 speed bike. I will be welding a platform for it to sit on.

Then I will be removing the pedals and putting a jackshaft to connect the crankshaft on the left side to the existing gears on the right side.

I will be using a centrifugal clutch off of the motor to get me going (along with a quick kick) so this will allow the motor to idle when stopped and get me up to speed when I put the throttle on.

My question for you all is: would the gears be able to withstand having a motor on it? I have heard of shift kits, but I really dont know what those even do. They just say it allows you to shift. But cant I do that in the first place if I'm using a jackshaft? And since I will be eliminating the pedals, and running the jackshaft from the opposite side of the 3 main sprockets, won't I be able to use my gears as usual?

Sorry for the long winded question. Your help is greatly appreciated.
 
Before you go too far, check your local laws. Most states will call it a motorcycle when the pedals are removed.

Tom
 
as long as it is under 50cc it is a motorized bike/moped. I plan on removing the decal and painting on a 49cc where the 99cc label is on the motor. The police here are nice lol.
 
The reason why the shift kits work is the china kit has a 4 to one internal reduction in the engine to output shaft. The shift kit also has reduction.
You would need double jackshafts to reduce your ratio in a huge manner.
Click on the Sick bikeparts ad on the left side of this page and look at their invention.

I suggest you keep the pedals and entire right side chain set-up (wonderful when you have something go wrong on the engine side drive- beats walking totally).
Look at the setups in DYI or 4 stroke sections.

Here is what I would do if I ever build another ride> Engine to jackshaft (belt)> jackshaft to sheave mounted on rear rim (belt). Simple, bulletproof, cheap and clean.
 
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