ORIGINAL: Tauri Flyer
I have the same engine. They are high compression and your going to need better then your average 12 volts to crank it. Even the Dynotron has trouble at 12v. I use a 2200mah 4 cell lipo,,works perfect! Also you'll need to get that motor wet to start it and fuel draw with hand cranking just doesn't get it on that motor. Shoot it a prime and bingo!
Well, not all 12 volt batteries are created the same, as you certainly know. While a 7 amp hour battery wouldn't start the Q35 with a standard Sullivan starter, hooking it up to my 450 amp hr 12 volt car battery most certainly did the job.
I do agree that a heavy duty starter with large surface area brushes and properly proportioned commutator rings, along with a large capacity battery, will certainly do the job. I wouldn't do it with more than 12 volts unless the starter manufacturer recommends doing so, or if you don't mind replacing brushes periodically.
My big Chevy van battery powering my standard Sullivan starter would definitely snap over a 50cc engine, but I don't know how long the standard Sullivan starter would last in that type of service.
Ed Cregger