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Building a motorized bicycle
Back in the summer of 2008, I decided to put together a motorized bicycle. Of course gas prices in and around the 4$ per gallon range influenced me to look into this. After a bit of studying on this, and looking around to see what was available, this is what I struck upon. Realistically, and not counting my labor, I have about 275$ dollars into this, but you could get by much cheaper if you already have an existing bike to use.
I chose to buy and off the rack Walmart Bike for 99$. Pictured to the right is the bicycle just after I got it home. It's model type was a Kulana Moondog. The orange and black theme along with the Cruiser style wide handlebars and big street tires would blend with the engine kit I had decided upon. This kit was a black engine with black teardrop gas tank I purchased off e-bay for 148$. The engine is a 50CC 2 Cycle gasoline. A 2 cycle engines will require oil to be mixed with your fuel.
The engine kit was produced in China and of acceptable quality for my expectations, which were not extremely high. When buying an engine of this type you will need to be at least somewhat handy with a few tools to install it , as it probably will require some tinkering around with to get it to fit correctly. Using hindsight upon this build, the job would be easier if you went for the simplest bike frame possible. A bike frame with small and straight diameter tubes of about 1.5 in. would be the best choice.
Your first major task is to mount the drive sprocket to the rear wheel. Remove the rear wheel to begin. On the left hand side of the wheel mount your drive sprocket to the outside of the spokes centered on the hub. The drive sprocket is held to the spokes using a segmented ring and bolts that mount on the inside of the spoke ring. Be as precise as you can be on centering this drive sprocket, then remount your rear wheel, just as you disassembled it earlier.
Next mount the engine to the frame as per its included instructions. Since the frame of my bike was bigger than the included mounting bracket, I modified the mounting using a 2 inch muffler clamp. mount it tightly to the frame and in the same plane as the drive sprocket on your rear wheel. This will lessen the stress on your drive chain by getting this alignment as close as possible.
With the engine in place you can mount the gas tank to the bicycle top tube, being careful it is positioned to not interfere with your steering or your ability to pedal. I purchased some rubber fuel line and a inline lawnmower gas filter at the local AutoZone, to replace the clear rubber tubing that came with the kit.
Photos follow on the next page ...
