The older Troy-Bilt Horse rototillers are a decent tiller, but a bit under powered for my taste. With a new BCS tiller in the thousands of dollars and tons of old Troy-Bilt's rusting in the wings - it seemed like a good project to convert one to a diesel. I realize it isn't clutch driven and I realize it isn't a Ferrari or a BCS, but to be honest; with the diesel conversion, it has plenty of power to make a big difference.
We used a Yanmar single cylinder clone made in China. These were plentiful a few years back until the EPA nixed them. Many small diesel generators use them, but it would be best to change out the tapered crank shaft to a straight (available on Ebay for about $100.00).
The conversion is easy. The diesel has the proper bolt pattern for mounting bolts, but the shaft is too long and is larger. We simply machined an aluminum spacer block to fit between the engine and the Troy-bilt frame and bored out the original Troy-bilt belt pulley. After broaching a new key way in the pulley, we assembled it
Detractors said it would rattle the Troy-bilt to death, it would be front heavy, it would have too much torque for the transmission, that the belts wouldn't last, etc., etc. - but none of that is true. The tiller runs great, it's well balanced and only shakes a bit at idle (which we don't recommend much anyways. Diesels like to be run at faster RPM's). The only troubles that we have experienced with these engines is the valve clearance needs to be perfect. Set cold, both intake and exhaust need to be exactly 0.15 mm. That is a crazy clearance. Set too wide, it beats the engine up, too tight and the exhaust is like a flame thrower. Keep the valves adjusted to exactly 0.15 and that engine really performs. With a set of wheel weights, I am sure it could pull a small seated trailer with no worries.