krexken
Zone Head
Posts: 732
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posted November 16, 2007 10:34 AM
Wrist pin galling
Just tore apart a JE pistoned motor and 3 outta 4 piston pins have slightly galled in the rod. All still moved freely on the piston. Wasn't very difficult to remove them either. Just wondering if anyone else has noticed much of this. I've seen it before on a 1390 that had a piston smacking the head but that was a much worse case. Piston skirts still look great.
  
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VincentHill
Needs a life
Posts: 6520
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posted November 16, 2007 01:07 PM
Is the extra Metal on the Pin or in the Small end? If it is ON the Pin then that is not good because you have removed Rod Metal. If the metal is in the small end then you can remove it and have no problems. I use an Abrasive rubber wheel / tipped Dremmel tool and a large magifying glass to remove the extra metal then with about 320 sand paper wrapped around a 1/4 inch shaft with a 2 inch slice! I put a little WD 40 in the paper and HONE the small end with a slow back and forth motion for a few times to get the "CROSS HATCH" back to that the Oil supply will have a place to reside. 220 Paper leaved too deep scratches that the oil is not thick enough to stay above the grooves depth and 400 does not hold enough oil IMHO (I have done this more than a few times to many different engines and this is where I am now with cleanning up the small end.
I do not know the exact cause but I think it is lack of oil caused by excessive RPM. load and heat!
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Made History @ Daytona and still one fast old man!!
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted November 20, 2007 04:19 AM
Typically pin galling is caused from the piston hitting the head. It doesnt take much contact either.
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Y2KZX12R
CompetitionCNC.com
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