Hi i have bought from SDS hobby a large starter for up to 80cc engines, it works fine for my 85cc 3W, the on/ off switches are not brilliant but the starter works well i have made my own adapter for the prop drive but you can buy them from SDS. It has a 6 to 1 gear reduction so hang on.
The starter costs $46 dollars.
I run it off a well charged 12 volt car battery or a 5s lipo.the lipo is about 18 volts and it takes this no problem
Super Big Starter (Can use for 80cc gas airplane)
http://www.sdshobby.net/super-big-st...lane-p-2149.ht