It all started in 2012 when my dad dropped off a broken chainsaw at my house. He said, he paid a guy to fix it and it never really worked right after. Maybe I could fix it and have it. It ended up being a 36cc craftsman chainsaw which was the same as the 36cc poulan chainsaw. Well I found out the issue. A leaking crankcase which is crucial to a 2 stroke engine for proper functionality. Anyway, I got an idea somewhere to try and use it to build a motorized bicycle...

I did a little research on the net then sketched out how I would try and build it. That weekend I went to the fleamarket and found an old bike that needed a tire for $30. It would work. I sketched out on a piece of paper a rough design, pulled out my sawzaw and stick welder, and got busy!

Since the plastic case of the chainsaw holds the crankcase and cylinder together, the whole engine came apart as soon as I took it out of the case. So I had to build a custom motor mount and buy some longer bolts to hold it all together. The hardest part was probobaly the custom motor mount. The plastic case of a chainsaw also holds the magneto in place (crucial for proper ignition timing). I had to carefully mark it's position to the flywheel and build it into the motor mount. Also it was important to insulate the magento with fiber washers since grounding the it kills the igntion.

Originally the gas tank was a gatorade bottle which did not hold up well. The new tank is a 1 liter fiji water bottle which seemed to be what people were using for fuel cells on hobby aircraft! Ugly but functional.

At first, I designed a spring loaded scisor clutch to start the engine but I kept having problems with the cables streching. I couldnt figure out how to start the thing with the motor mounted on the tire. My dad got on it and started petaling and the thing just fired up! You petal to start, and it stalls the engine when you stop. Works awesome! I connected the throttle of the carburetor to one of the bike's gear selectors. I didn't need the extra gears and it actually doubled as a slightly dangerous cruise control. The Spring that holds the motor against the tire came from a trampoline.

I could not find an M8 1.0 reverse thread nut to fit the driveshaft anywhere in town or on the internet so what I did was disassemble the clutch and cut the center out of it. I was going to weld a nut to it however I left it in an oval shape so I could tighten it with channelock pliers. Hmm seemed to work! Next! The socket is a 7/8" 3/8 drive drilled out slightly bigger to slip over the driveshaft. A washer sits on the driveshaft shoulder to the socket from sliding all the way into the cyclinder jug.

The only major problem that I kept having was the crankcase seal kept leaking. The exact problem that broke the original chainsaw in the first place. I ended up taking it apart about 4 or 5 times and trying different sealants. Nothing seemed to work (evidenly the permatex I was using was expired). I ended up using orange hi-temp RTV permatex which is not rated for gasoline, but it held up just fine.

After running several gallons of fuel, I calculated that the bike gets nearly 100 miles per gallon and according to the GPS zip tied to the handlebars, it has a top speed of 34 mph. Fast enough that I needed a helmet. On the street, people looked at me funny when they saw a bicycle passing them on the avenue. After months of riding this thing, I let the little brother of a friend borrow it. He painted the bike then entered it into the county fair where it won 2nd place for FFA projects. Not exactly ethical I know, but I'm still proud haha.

Now for the bad part.... He brought the bike back back wrecked. I mended it the best I could but the motor mount had broken. I eventually threw it in the scrap pile. It wasn't a bad little device for a project less than $100. This was my first motorized 2 wheel vehicle and it got me hooked real good. Since then I've owned 9 different motorcycles over the years and am still in love with 2 wheels today!