BMX to Motorbike Conversion





Introduction: BMX to Motorbike Conversion

Well ok i took my old gary fisher bmx bike. Took my old mcculloch 32cc leafblower. I stripped it down to just the shaft and engine and well youll see the rest

PLEASE NOTE; this is just a experiment to try out instructable I will make a 1 on 1 video and take u through the whole process soon

Step 1: Mounting the Peg Onto the Engine

Well ok the first thing u want to do is jam the flywheel with a screw driver this allows you to work without the engine spinning freely. Well for my friction shaft i used a normal bicycle peg i would recommend using a 3 inch peg because i used a 4 and that was way too long. The engine i was using has a 5/16 keyed shaft. This was extremely difficult to work with considering it was only 1 inch long and u have 2 fit alot of stuff on it. The pattern i used to lock every thing in place was in this order a skateboard bearing, bike peg, lock washer, nut. This pattern seemed to work very well.

Step 2: Mounting the Engine on the Bike

well there are thousands of ways of doing this but the approach i took was pipe clamps and nuts and bolts. First of all because i dont have a welder yet and i dont want to ruin my bike. Well since backpack leaf blowers have anti-vibrational spring i used those with a nut and bolt and those thing that go around a handle bar that u have ur bike reflector on except metal. on other areas i just used pipe clamps because i can adjust those easily. For the friction to be applyed to the tire with force i used a very small spring on the mount closest to the shaft for the most leverage. Do remember that this bike cannot idle so you must start it and then run with it and jump on :) Spacecadet505 does not take any responsibility in injury by the machine or human error or anything else:)

Step 3: Go for a Ride

DO NOTE that i have tested this invention and it is not 100 % my main problem is just how to get enough friction on the tire please leave comments with ideas i will appreciate them.
Go for a ride!!


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    47 Discussions

    I built one few years back with a 1500cc Homelite, i call it my weed chopper

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    You might want to add a counter weight for the motor on the other side and maybe remove the pedals and attach them further away from the engine but other than that great idea

    You could make this safer if you improvised a brake handle and cable running to the motor. That way you could pull the peg away from the tire when you wanted to idle. A spring could pull it back into place. It would work in the same sort of way you tension an alternator for a car engine. You would need to mount the motor on a pivot first.

    2 replies

    you mean it would be a manual clutch.... that would be more dangerous if you had a larger motor, you have to consider all of that kinetic energy being transfered in almost an instant to the bike. As soo as the flywheel hit the bike you would wheelie and potentially hut yourself

    Fixed roller systems (no centrifugal clutch) were in use on some British bikes of the 1900s. They employed a handlebar kill switch for stopping, and pedaling for take-off and engine start. If you have a lift-lever for a "clutch", you will do fine as long as you can move the bike up to the engine's idle speed or better before engaging, or endure the tire scuffing under throttle to take off.

    Look on for home-built friction drives. Machining the roller will work a LOT better than trying to weld anything on it (lines, grids, etc) or epoxying sand.

    It's better to have a bike that you can pedal normally, with the motor on the back, or on the fork. A handle-bar mounted kill switch is a good idea if you do not have a clutch.

    I have a friction drive bike I made with a kit from Thats Dax, and a Japanese industrial motor. It works great, has a huge clutch, and a Quick Release to move the roller off the tire. You can put one on a BMX if you want, and it's possible the leaf blower engine will mount to a Dax friction drive kit. Also there is Staton-Inc, which offers more clutch drum sizes.

    Well you could weld lines down the peg all around it that would give it enough friction !

    nice instructable, im planning on making something like this with an old chainsaw

    Looks nice.  I plan on building another motorized bike soon.  It will be friction drive also.

    FYI, you can't just put a sprocket on because it would not be a low enough gear ratio.  You will need about 35:1, perhaps 40:1 for a weedwacker motor.  Otherwise it will just bog down the motor.

    if you put a small bike sprocket onto the shaft you could put it on the chain

    try connecting the shaft to the crank instead of the wheel

    great ible 5 stars

     if I get around to it, I'll try this on my bike with an old weedwacker, but honestly I'll just go for a new centrifugal clutch, or a manual handlebar mounted control, then directly chain it up, effectively making it a trailbike type thing rather than a motorbike :S

    You may be able to find a piece of rubber hose that will fit over the peg. It will need to fit much like a handle grip fits on handlebars.

    I think you should mount the engine about 1 1/2 to 2 inches away from the bike so the grooved rough part of the peg makes contact with the tire instead of the smooth part.

    mount the clutch on the engine shaft and run a bike chain from the clutch to the new gear on the pedal shaft