I have yet to do that..... I was surprised they don't have more power than they do, also. as I said earlier,...."I figured they'd be kind of wild as far as electric motors go ". you know,....torquey little buggers that want to jump out of your hand when you hit the switch. but even with a .46, if I bump the prop up against the compression stroke , put the starter on the spinner and then hit the switch, it will barely get through the compression and if the batteries aren't freshly charged, it's hopeless. I have tried this with a larger battery as well, thinking maybe the little cycle batteries just don't have the oomph, but it made no difference. I kind of consider the starter a failure on my part for the decision to buy the one I did. they might work OK on a four stroke, where there is a chance to things spinning before hitting the compression, but on a two stroke, they don't stand a chance and if the engine is new and tight, they are useless. I can't imagine either one of mine bumping over a .90 size two stroke.
I have a small electric motor rebuilder in my town. I was thinking of taking one to them and seeing if they can rewind it for torque, but i'll bet it's most likely the magnets that need to be stronger as much as the armature windings need to have bigger gauge wire.