<div class='quotetop'>QUOTE (6Mile @ Jan 19 2007, 01:48 PM)
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<div class='quotetop'>QUOTE (CFM-Z440 @ Jan 18 2007, 11:58 PM)
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Look at the piston crown. No wash at all! LEAN
There is a very small amount of wash on the better piston. I wouldnt call it a cold score because it was too lean to live no matter what happened. I would say that it was way lean, but didnt have wide open throttle long enough to start detonating or to blow a hole in it.
Kind of looks like a possible lubrication problem also. Maybe caused by the excessive heat.
I dont think it is a cold score because it is all the way around. Cold scores are usually found in the "four corners"
Hopefully your rods arent blue where the wrist pin bearing goes. $$$[/b]
Exactly,
This is why I think there are a couple of issues that have compounded and caused the failure. First is a Lean fuel mixture in the mag cyl that failed. The second is a lack of lube. both sides are showing signs of this. Look at the "good" piston on the exhaust side, there is scoreing there as well.
Lean Fuel and lack of oil = squeeeek
Resolution:
1. Replace parts as needed
2. prelube cyls and crank put back together with out the carbs installed. Start to clean the carbs.
3. Blead the oil pump
4. put drill with socket adaptor on clutch bolt. and turn over crank and verify that the oil pump is pumping oil to the intake boots.
5. If not blead the pump and repeate #4.
6. Clean the carbs again.
7. install carbs and run it with 50 or 75 to 1 premix in the gas. ( Plugs are cheep)
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Thanks for the advice. The only thing that is making me wonder about being lean is that I have driven about 300 miles on this sled so far this year and I didn't change a thing between the first ride and the last. And the other times I was riding I was wide open throttle for minutes at a time.
I have an older friend doing the work for me, so I'll show him this, and see what he thinks.