Bought the bike blown up and did a full frame up rebuild. Had the crank rebuilt with a wossner rod, wossner piston, all new OEM bearings and seals, oil pump, etc.
First hour just putted around the neighborhood and did a few heat cycles with cheap Honda 10w40 oil and then switched to yamalube semi-synthetic 10w50. Put another 2hrs pretty much just putting around my neighborhood. I can't remember if I changed the oil again around this time. Then did a glamis trip where I was mostly in my sxs so maybe 2hrs there. Then did a guys trip to Southern Utah where we rode mostly single track and put another 5hrs on it.
Last day bike started ticking. Was hoping it was the cam chain tensioner so put in a dirt tricks and it didn't go away. Pulled oil screen and found copper flakes. Tore in to the engine and found a little play in the crank. Split the cases today and there was quite a bit of copper sitting in the bottom. Couldn't find any oil pump issues. So lack of maintenance or just bad luck? Worse case was it had 8hrs on oil after 1st oil change.
Who rebuilt the crank? That's definitely a bad big end. Possible it was improperly pressed in (either too much or not enough).
I don't want to throw the crank builder under the bus without knowing for sure it was something done wrong. He's very well known in the KTM engine building world and I have only split the cases on like 5 engines so the chances on it being something I did over something he did is more likely lol I just can't see what I could of done to cause it other than changing the oil more frequently. Did some hill racing at the dunes but it never saw the rev limiter.
I would reach out to them just explaining the situation. They might have a better idea. Was the crank centered in the cases? For a failure this drastic, this soon, something was binding it up. I wouldn't think it would be a defective rod either, given you're using quality parts, but I suppose anything is possible. At least you caught it before it really let go.
I lost a crank on a 100 hour 17 350, rebuilt it and lost another one a few hours later. Had the same handful of copper shavings you have. Turned out the oil squirted was clogged. I don’t know if that caused the first failure, but it definitely caused the second one.
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I checked the passage way and didn't find anything. Plus before assembly I had ran the cases through the ultrasonic cleaner. Idk going to rebuild it again and hope for the best lol
The oil squirter is to spray the under side of the piston, wouldn't really cause a crank bearing failure if it was blocked. The crank is fed with pressurized oil thru the clutch side cover. Make sure the seal in the cover isn't torn or damaged. Thats a plain bearing crank so proper oil pressure is especially crucial. Also, make sure your crank end play is in spec when assembling. Might need to shim it
Yea after looking at it all torn apart i found the oil passage in the clutch cover with the seal. Definitely didn't replace it last time but will this time. I can't remember if I checked end play last assembly but definitely will this time.
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