Interestingly enough, my starter is the Tower Hobbies brand, which originally had the Hobbico power pack. I have since removed the Hobbico pack and wire tied a TorqueMaster 12 volt, gell cell, sealed lead acid battery directly to my starter.

This makes my starter package heavier, but it also has more power than the smaller Hobbico pack (which worked fine for a while). (I think the Hobbico battery is about 7 amps, while the battery I'm now using is more like 10 amps.)

I have let guys with fairly big engines borrow it at the field when their's is low on juice, and it seems to work well on engines up to at least 1.40 size. (It started a US Engines 41 cc engine once too.)
Dennis-