Tore my motor down for a rebuild because of a suspected bearing noise.
Guess i was right(in denial). Oh well, done is done, right?
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Click to view attachment

I thought it was odd that it was only on second main bearing and one rod were damaged. What ever was in there made a couple trips around then F'd off.

But was wondering if this burn pattern on the pistons is a sign of any thing.
only 50k on the motor. I havent check fuel pressure yet and whether the injectors are leaking. Did have a surging idle though, From stall to 900 rpm.
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Click to view attachment

Heres a better idea of how they burned. Dont recall ever hearing detonation. Compression on the 'clean' side is 110 and 115. Dirtier side is(1 and 2) are 125 and 120.
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Click to view attachment

Yea that is an odd burn pattern. It looks kinda like the start of a head gasket leak on a water cooled motor..

Nobody has any ideas if this is normal for 50k?

Looks like every motor I've torn down.

Thanks, I havent seen clean pistons before and thought it may be a sign of something.

Considering less-than-high-quality gas, for 50k...not bad.
Too bad about the bearings. I guess you can look at it as an "opportunity" to check everything out. How does the crank look?

cm

Makes sense.

Back in my dirt-bike racing days, we used carbon buildup (by adding extra oil to the gas) to seal off gouges in the cylinder walls (usually left there by previously exploding rings or pistons).