Join Date: Dec 2005
Thanked 1,063 Times in 934 Posts
07-08 Mileage: 2 few
06-07 Mileage: ^^^^
Picture shows NO SIGNS of valve contact (only a spot on valve being "apparently" from piece of chunked piston)...
Very little actual piston wash, instead, more "washing" going on right at transfer port bridge areas of piston dome... When this shows, usually from bridge building heat and making carbon (from unburnt incoming mixture due to low compression) recede... Chances are jetting was kind of lean prior to failure, but, the unburnt sooting afterwards masked this..
However, I have to agree with poster who mention piston skirt fatigue.. With the way these Cat twins of 650cc and larger displacement shook, I'd have to say piston had danced around for a while and weakened top of dome right above ring land...
Add slight detonation from leaner mixtures and usually the top of ring land suffers on these bigger bore twins (right out of 1992 performance manual referring to the 650-700cc machines of back then)... These 800/900cc engines were no different....
I'm suspecting the leaner fuel mixture didn't cause major damage overall due to massive BLOWBY that I'm sure will show once pics of complete piston skirts are shown....
Pull complete engine apart and clean good, inspect for cracks in crank cases just in case... Have the crank checked by reputable source for run-out (trueness.. .002" is max allowable), and don't use rtv sealers, get a tube of Three-Bond 1204 case sealant for reassembly (use new crank seals also)
Who, me?! Don't listen to me.... (I don't know anything, evidently...)
If it's cnote approved it will work good
That is freeking sick man........
0637-185: '99 Sno-Pro APV (guide and button) update kit p/n...
0637-186: '99 Sno-Pro APV superseded valve inserts update kit p/n...
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