08-04-2010, 09:38 AM #1
- Join Date
- Nov 2009
Crankshaft bearings contaminated?
Finally putting my 1200 pv back together. In cleaning up crankshaft with acetone, noticed that the two bearings nearest the blown piston spin "rougher" than the others. My fear is that metal shavings may have found their way in. Are these totally sealed bearings? Put a digital micrometer to the crank and am virtually within width tolerance (eg. 2.876 in measurement when spec'd for 2.872-2.874). Been blowing air between bearings and lobes and got some shavings out. Affected bearings spin freely, but it's almost like they aren't greased. What to do? If this is a problem, seems new crankshaft is the only answer as used would only be from failed motor with high probability of same issue.
08-04-2010, 10:00 AM #2
the bearings are not sealed they get lube from the fuel oil mixture, if you are getting shavings out chances are it is bad and a rebuild is due. I would send it to crankworks and have it inspected and repaired or go with a new OEM one.
08-04-2010, 10:28 AM #3
When i cleaned my crank, i cleaned the shit out of the bearings. After that i noticed they spun like shit (obviously because they were unlubed). I squirted Amsoil in the bearings and kept spinning them and re lubing them.
08-04-2010, 02:58 PM #4
Spray with brake cleaner, then compressed air, and repeat. DO NOT spin the bearings with the air though...just use it to blow contaminants out. Hold the outer race with your hand. After you're sure you got everything out, relube with 2 stroke oil and feel them for roughness.
08-04-2010, 04:10 PM #5
Once the small metal shavings get into the bearings, they start to eat away at them. You can try to clean them out but your asking for it IMO. These bearings are out in the open, i would not chance it but its your call. Sending it out to Crankworks for full inspection is the right way to do it. If you put it back knowing the bearings could be damaged then get ready to take it apart again. A crank bearing can take out alot of parts. The crank is the heart of the engine, why chance it?
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