That reminds me of my days as a kid messing around with go-karts. My dad is a mechanic, and has his own shop, so we had lots of fun souping up B&S 5hp motors. After the compression got high enough, we weren't able to easily start them with the recoil starters anymore. The solution? Take a automobile starter motor, put a couple of handles on it, and weld on a bit of square shaft. We drilled out the rivets and took the recoil starter off, and you're left with the part that mates with the new starter. Add a switch, hook it up to a battery with jumper cables, and off you go. May work for you as well.