The Hairy Beast

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…

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     then i got to work.

1.      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…
3. 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.

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.
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.

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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.