metal shavings and chunks found

[clintcook]

Hello,
After taking off the cylinder and removing the piston, rod bearing locks up periodically possibly due to quite a bit of metal found in bottom of case. When spinning freely the crank bearings feel smooth, then all of a sudden the rod will seize with a chunk. Any thoughts as of what the possible culprit of that much metal might be? So far the easily visible gears seem fine, have not split cases yet, timing chain was fine and tight. Thanks for any feed back.

[cannondale27]

Big end rod bearing.

[clintcook]

Thanks! Will be splitting cases hopefully 2moro, hope it is coming out of the tranny.

[cannondale27]

Convert it to a WR crank and piston with squirter and inspect your shift forks in tranny and you will have a very stout and powerful motor.May as well make it worth your time taking it apart.Even then you just cant expect it to last forever though.Always recommend 2years at most on bottom end and 1 year on top for any 450 based motor any brand.Is just the way it is.

[Kovatch]

I ran into some issues on my YFZR. The cranks blow on these motors; hence, why there is an updated part number for replacement and the WR cranks are popular for the yfz motors.

Usually the rod and crank have an issue with oil and the rod tends to start shaving the crank. I was at Baldwins and saw this first hand. Sure enough my engine blew and it was the same thing. It looked like you shaved a chunk off the C-rod. Check the water pump inpellar too. My was chewed up pretty bad. Look at the valve springs, crank bearings, shims, cylinder, etc. You never know where the metal may have come from. I just started replacing everything that looked the slightest bit scuffed/fatigued. If you're in there, why not freshen things up.