ORIGINAL: GR7Racer
The bearings look and feel fine, but I did find a lot of dark paste on the outside of the front seal of the front bearing. I'm wondering if I have just cooked out all of the grease/lubricant in the sealed nose bearing? Should I just pop both of them out and change them or is there a way to evaluate them? The sealed nose bearing feels very free, but not sloppy.
K
That is a sign of the front bearing outer ring spinning in the crankcase. The fit gets loose if the engine runs too hot. Once at that point, the tight tolerance between crankshaft and crancshaft bore is exceeded and the shaft rubs in the bore causing extra friction, extra heat, extra friction, etc..
To check this, watch for rub marks on the shaft.
todo:
- replace the front bearing, and use loctite 648 to fit it in thecrankcase.
- fit the crankshaft in the case, then chuck the shaft front in the lathe and while holding the crankcase, check for wobble. Tap-tap with plastic mallet until running true. If lathe/chuck is old, you may need to make a true bore first that will hold the shaft front end, or use a 4-chuck.
- Check engine cooling. Is the liner straw - blue colored? it should not be!