this is intended for the Instructables Bike Month of May contest, so please vote, I would really like to get a t-shirt. they are cool.
I'm not responsible if you hurt yourself/others/things/stuff in anyway. Also if you make something that is illegal and get caught don't come running to me, its up to you to check the regulations in your area for motorised pushbike.
This is also my 2nd Instructable so please be constructive and supportive.
Step 1: Stuff You Need
you will need:
- a bike (any will do, but the simpler is best ie. no rear shocks and stuff because it just complicates things, although still possible)
- a motor of some kind, preferably small but with a fair bit of power, a clutch is nice because you can ride it normally without the motor on, although still possible without. and if it has mounting holes or something that will make it easy to strap on your bike. I used a small 2 stroke whipper snipper motor made by kawasaki, bit gutless as I'm 85kgs but I had a bigger carburettor on it before when I was mucking around with it.
- a bit of thick plate to use as the mounting plate/bracket. thick stuff is good because it hold your motor nice a steady.
- a roller/driver shaft to run on the back wheel to transfer power to the wheel. size is important as it affects gearing and therefore final speed. I did the math and figured out it needed to be bout an 25mm - 40mm in diameter to get around 40-50kmh
- miscellaneous, tooling, ie screwdrivers, spanners, persuasion tools (big hammer and shifting spanner)
- an oxy-acetalyne set is nice to bend your plate if it needs it
Step 2: The Motor Mounts
it basically would hold the motor by the 2 bolts that also held the clutch on and in its previous life (as a functional whipper snipper, the wire stand). I forgot to take a photo but its pretty simple.
Threes so many different bike shapes and motor mounting designs, so I'm not going to tell you how to do yours, (unless yours is same as mine) so you'll have to figure out the shape and/or mounting style for your bike/motor.
when you have your motor mounts ready to be fixed to your bike. you should just "tack weld" them on first because you will probably have to adjust them as you want a fair amount of pressure from the drive shaft onto the wheel but not too much that it hard to turn.
Step 3: The Drive Shaft/roller
I had sum bike pegs I was going to use but they had imperial threads and my clutch used a metric thread and I didn't want to make an adapter so I decided to make my own.
I needed a lathe to make my own but so dad knew a bloke with one and he made it for me. it fit nicely into my clutch housing and threaded right into it.
the size of the shaft/roller matters as it affects the gearing of you bike. you will need to work out revs of your motor, size of your back wheel, how fast you want to go etc, to decide on the size of the roller.
Step 4: Mounting the Motor
if you motor is sitting at an angle to the bike this is wen you may need to heat your mounting brackets and give them a bend to make it sit straight. or if u really screwed up, u can cut the mounts off and reweld them straight.
make sure that if you are holding the bike in a vice like i was that the bike is the same level as if it was sitting on the ground!. mine was tilting back so when i leveled the motor and then sat it on the ground the fuel tank was leaning back and i had to chock it so that the fuel would flow throught the tap.
Step 5: Mount the Throttle
Step 6: Riding
Also check the legality of these kinds of mods, in NSW, Aust, to be legal it must be under 800watts of power and under 25cc or something. Iâm sure cops would love to book someone causing trouble on a motorised pushbike.
My bike when the engine was running nice did 40kmh easy on flat. I put nitro fuel (15% nitro methane, the stuff used for R/C cars) in it one day and it went ballistic, it scared me.
The clutch on mine wore out pretty quickly coz its old n Iâm heavy n didnât want to pedal at all. But if your light or have a more powerful motor u donât have to pedal ne time except for start off and really steep hills.
Thanks for reading my instructable and please vote for it in the Park Tool Bike contest!