Quote Originally Posted by agent4573 View Post
Instead of gears it would be better to just add a centrifugal clutch from a small go-cart or spend the money and get a constant velocity drive system for it. All those little crappy 2 horsepower go carts get going from a standstill, then this bike can too. It'll add a bit of weight and some noise, but it should be able to get you going from a standstill.
Quote Originally Posted by Rambozo View Post
But without a positive clutch, you would need another method to start it. I'm sure with a few tweaks you can get enough power to have a standing start. I see some of those are tweaked to go 50+ MPH.
Quote Originally Posted by Jason View Post
The more I see this, the more I want to build one. If you added gears, do you think it would be able to take off from a stop?
Absolutely. You can buy a jackshaft kit, which replaces the bicycle's front crank and runs the engine's power through the bicycle's existing gears.
I've seen people getting up to 55-60mph with gear kits like this, and they start from a stand-still using the engine's regular clutch... so they still start the same.

Another option for adding some fuel economy, get up and go, and top speed, is to use an engine out of a little dirtbike with a CVT transmission (and a kickstart). I plan on building myself one of these with a 50cc 4 stroke engine from a dirtbike with a CVT transmission and an auto-clutch. with the CVT the engine can be even smaller and ends up working better.