Go to a home improvement store and buy a weed-eater with a 31cc Ryobi in it. The cheap weed-eater (approx. $76.00, which I use) will have a Short-shaft crank. The more expensive Ryobi weed-eater will have a long-shaft crank and clutch-unit, which could also be used. Go to Jag Engines and by a conversion kit, long or short-shaft, jagengines.com . This will include the motor-mount, prop-adapter, and carb spacer. You can run this engine stock out of the box with this conversion kit, which I did for a couple of months and had know problems at all. Great for a Cub or airplane that does not require a great deal of power. The stock carb for the weed-eater is on the small side and had sealed needle-valves. For more power get a wackerengines.com big-bore carb & a Jagengines.com round muffler for a large increase in power. For less than $200. I have an engine which I just love. P.S. - Do not over-prop the engine the big carb needs the rpm's to breath. (Lot of fuel-lot of airflow in carb) Have Fun: Ron