X3 with one exception. Measure how far the piston is in the hole before buying the rod. Otherwise you may have the shave the piston if you go to much over on the rod. Ask me how I know that lolWhat he said. and ad good valve springs and a honda 390 carb. Cheap knock off on ebay for 25 buck will work and arc adapter for carb. Built one like this. 22hp and under 500 bucks.