The gasket pictured looks fine, but the backplate suggests there might not be a steel shim/washer between the propdriver and the front of the crankcase. There should be, most especially if you use an electric starter. The swirl on the face of the back cover indicates that the steel shim/washer is probably missing and possibly the use of a starter or LH propellers.
Allowing the crankpin to rub on the aluminum back cover will send aluminum through the engine, and the result isn't good. If the engine's life isn't important, the glowplug life will be short and drain your kid's college fund quickly, due to the current high price of glowplugs. 
Steve
I have seen that on nearly every plain-bearing engine I have ever taken apart, it's not from the crankpin, it's from the conrod getting pushed off the back of the crank. I think that is normal. I would only do anything about it if the crankpin hits it, and that usually has plenty of clearance.
Note that this is why Marvin Denny invented the Fox "stuffer backplate". It wasn't for performance, it was to keep the conrod pushed up onto the pin, to reduce wear on the rod bearings. It had nothing to do with performance, it was durability when run hard in Foxberg racing.
Brett
Topic: thickness of the crankcase gasket for an OS MAX 25 FP? (Read 892 times)
