The old blue engines had a crank shaft diameter of .316" while the new ones using the same needle bearing have a .315" leaving a .001" giving us a bit of slop. Still it doesn't seem to hurt. I have no idea why they began using crank shafts .001 undersize. My old blue M90 has many many hours on it and still has no slop.
The correct solid bearing material if anyone wants to try it is Oilite bronze.
Oilite is a porous bronze or iron alloy impregnated with oil.
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