3W 170 Piston Pin

BVargas

3W Flyer
Hey Tired Old Man, any speculations as to why this ocurred? 1 of 2 things perhaps,,, pin stopped floating or it was just a P.O.S. pin. Has about a little more than 3 good seasons on it since the last rebuild.

Sthil @ 45:1 No piston heat discoloration,,, upper conrod has a little discoloration but no bluish hot spots. About a 20 thousands step on the pin. All the rollers are still there and the cage has some heat dicoloration as well. Oil passage was fine and no blockage. The other side is just fine.

A new pin and bearing fits just fine and engine runs good like it always has,,, I think I got lucky that it didn t grenade itself at the wrong time.


BV
 

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Tired Old Man

Staff member
Recently learned that 3W had been shipping some engines that did not have assembly lube used when they were originally made. It's possible most of that happened in the first runs of the engine. It's also possible the piston pin race was undersized a little when it was made. I would expect a new pin would be an easy fit after that much friction at the race. Personally, I would not use the piston again.
 

BVargas

3W Flyer
Yup, I hear ya on the preference. Ran about a gallons worth worth today. Started out fat, tweek the needles some and worked out ok. I did move up on the oil some going from 45:1 now to 40:1 and seemed to be ok.

Thanks for the info T.O.M.

BV
 
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