Gas Powered Longboard

http://www.youtube.com/watch?v=uUymo7rTnZg

     So after last winter semester I had two weeks before starting the summer term. With Maria still in work it was up to me to entertain myself. Honda sells its 200cc horizontal shaft engines for about $350 but I found out that Harbor Freight sells a clone of that engine for $160. Right before my break that same engine went on sell for $100, and with a coupon you could pick it up for $80. I could do an entire blog post about the good, the bad, and the ugly of Harbor Freight, but needless to say, an $80 engine gets my mind working. I picked one up and brought it home and started making plans. The problem was I only had one engine and couldn't decide what to throw it on! I could put it on my commuter bike, I could put it on the recumbent, or the tandem bike, make a go kart, or throw it on our long board. They all sounded like fun so I started thinking of a way that I could do them all. What I came up with was kind of a modular idea so I could quickly change it up. I decided the easiest way to do this was as a kind of a push trailer that could be easily attached to various objects.

Most of the parts I needed could be found from gokart supply stores, but ended up being a lot more than I was willing to spend on the project. The only part I ended up buying was a centrifugal clutch (it disengages the chain under a certain RPM so the engine can idle at rest). The centrifugal clutch has sprocket teeth on it that are made for a wider chain so they had to be ground down. I put the clutch on the engine shaft and fired it up, I now had a makeshift lathe! Using a grinding stone on the angle grinder I was able to uniformly grind the spinning teeth down so they would fit a bike chain. My cousin Mark Hsiao was nice enough to give me some extra wheels he had lying around, I used one as the actual wheel and ripped the hubs out of another two wheels and fab'd some adjustable mounts for them so i could use them as bearing mounts for the live axle. I made my own simple frame to hold it all together and welded a bike sprocket to the axle for a simple drive line.

It has a trailer hitch on the front that can easily be attached with different configurations. I wanted something original so I decided to start with the longboard which ended up looking like this.

The handle has a throttle, brake, and kill switch. 

Put it all together and this is what you get->

http://www.youtube.com/watch?v=uUymo7rTnZg

It made for a pretty exhilarating ride. The engine probably has enough power to get someone going over 60 mph, but the way I did the gear ratios it limits it to about 30 mph. If you don't think 30 mph sounds fast trying doing it on a squirly longboard. I asked Maria what we should call it and she just said "dangerous," understandably she was never a big fan of this particular project. I am still open to suggestions for a cool name, I am pretty sure we can do better than "gas powered longboard". Anyway, the back tire doesn't really get enough weight on it so traction is limited and makes it that much more squirly. Regardless, it is a blast to ride and there is just something special about bombing a longboard uphill.