http://racing.briggsandstratton.com/videos/maintenance-repairs/proper-clutch-installation I looked at this video on racing engines, but I expect that the crankshaft on my old Briggs's 3 and 3.5 hp do not need a radius washer between the crankcase wall on the crankshaft and the clutch or sprocket if no clutch used. There is no bevel to the end of the crankshaft on the engine I have. I attached picture of video at 1:14 of the 3:01 end minute mark which shows a racing engine crankshaft. At 1:12 there is the picture of the radius washer that must be used with a crankshaft like this. The other is my engine with no bevel. What is the need for a bevel, if I right that must use a radius washer, on a racing engine? Why bother making a crankshaft that needs an additional part when other engine do not do this like on my old engine?