Hi, yes they move in the crankcase housing. I have reduced this by using a packing shim. I have already stripped, cleaned, degreased and used the best quality bearing fit recommended by a local engineering shop. I had thought that the situation was caused by inadequate cooling of the lower part of the engine since I have a baffle directing the air over the cylinder head (Ziroli P51) but the application of a standard hair dryer is sufficient to allow the bearing/ crankcase fit to slacken. I have about 2 or 3 mm movement and I have been advised that this is Ok. What are your thoughts? Thanks for your input,