Hey all. I am in the process of tearing down my '05 WR450 engine. The engine seized on me while riding. My fault, after it seized I realized that the oil plug high on the frame was gone. The only thing I can figure is that I didn't tighten it well after an oil change.
So I figured I would get all the top and bottom end parts, and hell, the bike is nine years old with a lot of hours so I have a brand new bike after the build. I have the new crank assembly, bearings, piston, and gasket kits.
I have the engine out of the frame and I have the head and cylinder off. I realized that the piston was my problem. I guess the oil starvation caused the piston to come in contact with, and weld itself to the inside of the cylinder walls. Once I knocked the piston down enough to lift the cylinder off of the case the crank actually moves quite freely. I am confident the seizure was the piston/cylinder union.
I cleaned the piston shrapnel off of the inside of the cylinder wall and it all came off beautifully but I do have a small (less than the diameter of a BB) hole in the cylinder walls. So I know that these cylinders at NikSil right? What options do I have there save buying a new cylinder? Can it be replated or even steel sleeved by like LA Sleeve?
I am going to finish the bottom end rebuild. I want to see everything inside there is OK, plus I have the new crank and bearings anyway.
What else should I (reasonably) look at doing? The head is mostly what I'm curious about. What could the oil starvation have done to it? It looks absolutely fine. Even outside the oil issue, on a nine year old bike what would you do? I would rather not shell out the money for brand new valves but how far should I take it?
What else am I missing on a full motor rebuild? I've done a fair share of top ends on 2 strokes, but like many jumping from 2 strokes to 4 strokes I'm finally at the "4 strokes are more complicated and more expensive that 2 strokes" part of my riding life. I will never go back to a 2 stroke again! I love my WR, I just want to do this right. Hopefully without breaking the bank.