New motor
Under development The next motor is based around a TS. The stroke is 64mm with a 120mm Rotax rod. To achieve this the cases needed a considerable amount of welding and machining to ensure that the crank fitted but also retained stength as a very deep channel is needed in the cases for the conrod to have clearance. Additionally the cylinder needs to be 11mm longer than standard, using a Wiseco Suzuki TS250 piston. The motor will be 64 stroke by 70.5mm bore giving 249.93. The inlet was hacked off and completely filled in and a DJ reed inlet welded in its place, which happened to be the exact size needed for the bigger reed cage, YZ125. The inlet was recut and re-aimed, with ports cut direct to the transfers. Whereas previous motors have run 7 transfers, I decided this motor will have the standard 5 as per TS only the main and auxiliary transfers will have a greater area.

A bridge was welded into the exhaust port and it was widened and raised. Once the ports were roughed the cylinder was bored and an aluminium liner fitted with an interference fit. I decided that the standard spigot on a 225 TS is a bit thin, so the liner was machined to 78mm, and I bored the crankcase mouth to fit, similar to the Rapido 250. I then recut the ports through the liner, enlarging and re-aiming the transfers. Once complete I welded an 8mm plate to the top of the cylinder to get the final height correct. More to follow when time allows.

The new motor is now running but now needs a ne set of crank webs to finish, the first set were old rubbish. The first set were an old set of 62 stroke webs with an eccentric pin. I knew these needed replacing but wanted to try out the motor on the road.