Thought I would shed some light on a project my brother in law(troybilt) and I are working on, and are pretty excited about. We will be using a gusseted '88 250r frame, and the motor out of an '86 KX500 that I recently acquired for the power plant. I took the KX for a few laps around the property prior to dis-assembly, and the torque is unbelievable on this thing. It has a scary amount of power at every RPM range. We gusseted the frame about a month ago, and were able to strip the KX down and pull the motor last weekend. We sat the engine in the frame, and it fits surprisingly well. We will be utilizing the fabrication skills of Robl Engineering for the motor mounts, as obviously the stock ones aren't going to cut it. I will attach a few pictures of the frame we started with, the gusset kit installed, and the motor just sitting in the frame with an RE custom aluminum fuel tank mocked up. I hope to have more updates soon. Thanks!