This is the early BMS Boundy engine with 46mm bore, found on Lawn Cub and Pathfinder mowers. I am rebuilding this engine at the moment so I thought that while it was apart some pictures of the internal crankshaft magneto would be of interest.
3 large bearings support the crank which is good because it is quite heavy, you can clearly see the magnets and pole pieces fitted into the cases.
Biggest drawback in the design is that the case seals can only be replaced from the inside. Incidentally I have done my homework and rings and piston are the same as JAP Model 80 also being 46mm.
