Here you will see the process in which i built my bike. This bike was built for torque, looks, and most of all, functionality. it utilizes a 2.8hp 97cc engine, gets great gas mileage and speed, and also was built for a low budget of $70.
How it all started, it started with me finding and old bike in my neighbors trash, the bike was a magna great divide men's 26” mountain bike. When i looked at the bike i saw a motorbike it just looked like it deserved it. so i got to work, i made a friction drive weed whacker bike, then when i received a doodle bug engine(2.8hp 97cc) from my neighbor i knew i had to put it on there. so i did but i made another friction drive bike. it was pretty good but i saw many other possibilities far greater than that. so it got me thinking about putting’ the engine in the center of the frame. after a few weeks of measuring and designing i came up with this…
2. once the engine was mounted i got to work making the jackshaft mounts which require two pillow block bearings made for 5/8 round bar as i was using that for a jackshaft. once again i used angle iron but this time some pretty bike angle iron it was about 2.5” wide both ways and 1/6” thick. it was too bolted right into the frame.
- I dismantled then entire bicycle until the handle bars front fork tires and whatnot were all off so that i could paint the bike the color i wanted. Then this is where the fun begins…
- 1. first i made the mounts for the engine, i had to be very careful so that the engine would fit. for this i removed the gas tank and the air filter. the mount i made bolts directly into the frame. i used some 1” angle iron which just so happened to work perfectly. it put the engine at a slight angle but worked just fine. i drilled holes so the mount on the engine would line up and simply put, mounted the engine.
3. once that was done and over with it was time to order parts, i already had the engine a 12 tooth #35 clutch a 20 tooth #35 sprocket but i needed a sprocket for the back tire and another sprocket for that side of the jackshaft. i ordered a 41 chain sprocket with 10 teeth for the jackshaft (the part going to the back tire), a 54 tooth sprocket for the back tire(it was a sprocket from one of those 80cc motorbike kits, the sprocket cost about $30),and some #41 chain.
4. after the long process of waiting for the parts. once received i started putting them together. i first started with the rear sprocket for the back tire. with such a large sprocket it was a pretty tedious task. but i got it done. once i got all the chain and sprockets mounted i made a clutch cover.
5. a clutch cover was necessary because without it. my leg would probably be torn off from all the moving parts right there. so i was thinking of making the clutch cover out of fiberglass but me being inexperienced with fiberglass it would probably look like crap so i thought of using a pot instead, but in searching for a pot i found one that would fit but it was over $20, i wasn’t going to pay that so it got me thinking of what i could use, then one day sitting in my garage, it hit me, i could use a wheel hub off of one of my old go kart tires. and it worked beautifully.
6. once that was done, i started working on the chain going to the back tire. it didn’t have enough clearance, it was hitting the down tube on the rear fork. so i grinded it out until the chain had clearance. but when i was finished that rear down tube was grinded out to such a degree that it effected the integrity of the bike. so i went to have a piece of round bar welded to that part of the rear fork.
7. then i made a spring loaded chain tensioner for the back tire, in order to accomplish this i got some 1” flat stock and bent it to where i needed it to go. i made the part that contacts the chain out of two bearings i had sitting around.
8. then when looking at the bike i thought the seat needed to be moved back for looks. so I did it. here are some pictures.