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.

Comments

[Mr.Hambone]

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.

[PerfectPantaloons]

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

[Yard Sale Dale]

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.

[Yard Sale Dale]

Look on motorbicycling.com 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.

[TSC]

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

[Damp Cuttlefish]

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

[ElvenChild]

whenever I try to watch the video it says it was removed please put it back up

[duh-man]

same.

[qaswed]

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.

[sharlston]

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

[sharlston]

try connecting the shaft to the crank instead of the wheel

great ible 5 stars

[MrRodrigez]

 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

[abbynormal]

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.

[asterman]

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.

[abadfart]

what if you put a gear on the peg and put the chain on it

[Sandisk1duo]

then you can't pedal

[annas one]

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

[erikals]

yeah, good idea, use the brake lever that controls the back brake so u can use that for a clutch just like on real motorbikes,

[leedemo]

that peg looks pretty slick where it touches the tire, maybe throw a bunch of tight rubber bands (for lack of a better idea) or something on there

[dondonjordan]

the gears on the bike would be useless as the gearing is actually changed with different sized pegs you can use the same method to mount the engine to the front of the bike that way you can keep the pedals but if you have crappy engine you'll just stink of exhaust everywhere you go

[lil jon168]

were did you get your shaft

[dondonjordan]

you can use a peg from a bmx wheel you can get etched ones for more grip

[abecar12]

it looks like you have the engine mounted right on the tire so my suggestion is that you flatin the tire about 3/4 of the way and remount the motor on the tire as hard as you can without hitting the rim and fill the tire up with air again that should give you a lot of friction and if that dosent work you should get a tire with big tread and do what i said

[annas one]

you might want to do this to a gear bike for added speed

[annas one]

you would mount the engine onto the bike frame between the front tire and the pedals with the shaft on the oposite side of the bikes gears you would then chop the pedal arms off remove the remaining parts of the pedal arm on the gearless side of the pedals and replace this with another set of gears (from another bike)

[annas one]

ok so i have been trying something like this what you need is another set of pedal gears a horizontal shafted engine that can fit in your frame and a centrifugal cluch (with 41 sise sprocket/bikechain size gear/to fit on the engine shaftyou can get the clutch at tracter supply

[vanmankline]

Any update on the bike? What do you think is the top speed? I'm looking into a similar project, however I plan to install an idle pulley/gear and a drive gear/pulley on the left side of the peddles This will allow more freedom in positioning the motor. I would also be able to use the bike's 21 speed ratios as a manual tranny. The idle would allow a "neutral" position. Have you thought about repositioning the gas tank? I'm not sure on your modle, but I'm looking at placing it higher up so I can have more freedom due to the decreased size of the motor unit.

[savagemania]

You change the peg to a small rubber tire. This might help reduce the wear on the tread of the rear tire. I built something like this except using a chain drive and taking out the pedals.

http://www.instructables.com/id/Gas-Powered-BMX-Bike/

[killerjackalope]

Using the textured bit of the peg would be better for drive but that's not a bad conversion, it's also quite safe because the friction drive is self regulating to some extent... You can stop it with the back brake, no doubt the engine overcome the friction and spins freely I would guess. Mine was a strimmer with the engine assembly mounted up front on the forks, when you braked the assembly tilted forward coming away from the wheel... It was simple to control, you just got up to speed and pushed the assembly down on the wheel and the inertia held it in place.

[spacecadet505]

cool yeah ive been working on more things like this like a go kart stay tuned

[killerjackalope]

Hmmm I'm working on a few Ideas now, hopefully the result of the motorised projct will run well, bicycle with what I've now decided as a 12hp minimum, that's the largest engine I've got in stock atm... but with some fnacy gearing and dodgy welding it could be pretty special... The other one looks like it's a no go unless you know where to get some really, really big rocket engines... I'd like to see the go kart, I was thinking of one but I'm not too sure about what way to go about with the frame... my best idea so far involoves a 1.6L rover engine and gearbox, that may prove to be suicide, so it's on hold until I get a better idea/engine, maybe a motorbike engine and gearbox

[spacecadet505]

a motorbike engine would be ALOT better because it already has a gear box in it my friend is working on a shifter cart using a yamaha 175 2stroke engine. Using a 4stroke like a briggs and stratton would eliminate some mounting issues but also bring up other issues like the wear and tear on forinstince the torque converter.

[killerjackalope]

If you used a flywheel to smooth the power delivery the torque converter would live longer... If I get my hands on a motorbike with a working engine but it's wrecked you'll probably see how to make a quad bike from a motorbike or a how to make a go kart from. Imagine turning a fireblade into a quadbike, it'd be unholy, not to mention capable of killing you...

[spacecadet505]

if u want to see me starting this bike and driving dirtbikes and go karts my utube account is spacecadet505

[spacecadet505]

no actually i have the links on step 3

[killerjackalope]

I had a wee look, I have my hands on a bike frame with on of those wierd suspension setups that's just perfect for the built in engine, it's all on the rear subframe and is easily cut to add room fo the engine, still need a clutch though.

[GorillazMiko]

Cool I guess. I like the dog in step 3. ;-)

[dragonforce]

Great work. would it be possible to use a chain saw motor? or anything around that size as a motor?

[spacecadet505]

yes of course but chainsaws dont have the right clutch so that would call for machining. What i would recomend is using a weedwacker engine because they have a centrifical clutch with a sprocket look up weedwacker motorbike from davesfarm on youtube i know the guy and he did a very quality job on his using a weedwacker. Let me know what you decide to use.

[LinuxH4x0r]

Awesome! If you want more friction coat it in rubber, or just use it with a chain