Agree you need more battery. Lots of talk about a rechargable available through Harbor Freight (right price). I think it was designed for cordless drills. A lead acid lawn mower battery will work well, but weighs more. Until you get a better battery, one trick you can try is to start with the throttle closed when you start cranking with the electric starter. Have a buddy slowly open the throttle as you do, until it starts. With the throttle closed, there will be much less resistance from compression, and by the time you get inertia going, it will start.

I think this is the one [link=http://www.harborfreight.com/18-volt-battery-67029.html]HERE[/link]
You'll need a way to charge 18 volts.