I took my MS engine apart again to fit a new crankshaft. The tapered end of the Top Racing crankshaft is a little further out than the original. This is a problem for the fan, it rubs against the outer shield. I put it in a lathe and took 1,5 mm off the inside. I had the same problem with another fan cooled engine and a crank from another manufacturer, i guess the crank shafts are made for the aircooled engines like the Monza etc.