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Old 05-04-2010, 05:50 PM
XYZBicycle XYZBicycle is offline
Motorized Bicycle Newbie
Join Date: May 2010
Location: Los Angeles
Posts: 3
Default XYZBicycle - South Bay of SoCal

About Me:I’m not really new, but I have a new board name, and I just finished building my first bike last week. Primary purpose for wanting to build a Motorbicycle – When I was a kid, I wanted to mount an old lawn mower engine on bicycle – Now I’ve done it!

The Kit & the Bicycle
I bought a 2 stroke “China Doll” kit from BoyGoFast on eBay over a year ago. Unfortunately, the engine didn’t fit inside the Mountain Bike I had intended as a donor bicycle, so I went on Craigslist and bought a used Beach Cruiser for $60. Then I broke an engine mount bolt off while trying to replace it with all thread as recommended on a FAQ on these boards. Then my wife had a baby, then we moved, so the kit sat in a plastic storage bin, and I sold the beach cruiser.
Back on the job a year later, looking at Craigslist again, I found a small company selling beach cruisers for $100 right here in my neighborhood.

Broken Bolt:
I guess I could have taken it to a machine shop, but from what I understand, this is a fairly common occurrence, so I resolved to figure out how to do it myself.
I broke at least 5 drill bits in the process and snapped 2 bolt extractors. What finally did the trick, was heating up the metal with a Benz-o-Matic torch I had for doing plumbing work, and used an engraving bit on my Dremel tool that I had for building model airplanes. I am also now the proud new owner of a small Craftsman tap & die set.

Grinding Therapy
After spending at least 4 sessions in the garage getting the engine mount fixed, I had to grind out the sprocket to fit on the rear hub, then I had to grind down a retainer cap to fit inside the sprocket. After all of that was settled, I put the brake arm back on, but now the brake arm didn’t match up to the frame.
Taking my trusty Benz-o-Matic torch, I clamped down the brake arm to my work bench with a pipe wrench (I don’t have a vise anymore), heated it up, and bent it this way and that with a 2 pound sledge hammer.

The Build
The rest of the build went fairly smoothly. My top tube was larger than the mounting brackets for the gas tank could handle. I spent a session in the garage one evening trying to fabricate some metal brackets, but just wound up with some seriously mangled metal at the end of the evening. Then I went down to the auto parts store to see what I could find, and came out with some flexible muffler hanger metal.
At some point, I went back to the plastic storage bin to see what other parts needed to be put on, and there weren’t any – I was done!

Test Rides

The first couple of test rides were really hard. I couldn’t get the engine to turn over more than a few times if I wasn’t pedaling, and I could only pedal so far with the clutch out. Finally, I found a paved path in a park that went downhill, and just kept going up and down it until it developed enough power that I could keep the engine going on flat ground.

That Look

Even though I live in SoCal, it is amazing at the looks I have been getting driving around my neighborhood. For the most part – women scowl at the noise, and men grin from ear to ear.

It's a fairly routine build as far as motorbicycles go, but I figure you build your first one to know what you want in your second one. I received several compliments on it when I rode it to a pickup game of soccer in the park last Sunday, and last night I was just sitting in the garage smiling and looking at it while listening to the radio.

It's like I'm 16 again, and just got my first car.
Attached Images
File Type: jpg bicycle Engine block.jpg (97.2 KB, 54 views)
File Type: jpg Sprocket.jpg (103.4 KB, 38 views)
File Type: jpg DSC_0790.JPG (269.1 KB, 46 views)
File Type: jpg DSC_0791.JPG (290.4 KB, 47 views)

Last edited by XYZBicycle; 05-04-2010 at 05:56 PM.
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