Hi. Fitting all the pieces onto an RMS full circle racing crank I don't seem to have enough room for the drive pulley and the kick start engaging piece. 5mm showing on the crankshaft, but 3mm is the pulley and 5mm is the engaging piece. I did torqure it up and rode 100 miles but the the fan chewed up on the casing. Maybe the nut came loose/it was when I took it apart. The fan was clipping the oil pump inspection window rubber on the inside. Maybe that loosened it up. It disintegrated and the nut was loose. Is a 50mm bush to long for the set up on an RMS crank/what is the standard bush length ? Many thanks