Originally Posted by Yellow Pig
Took the head off the bike and can't tell what is causing the oil consumption.
Have a look at these pics and tell me if you see anything wrong.
Cylinder looks great:
Compression ring looks good:
Oil ring looks good:
Do these valve stem seals look properly seated? Not sure about this one?
Intake side valves:
Exhaust side valves:
It's definitely burning oil, lots of buildup on the piston and the face of the valves.
The back side of the intake valves looks pretty gunked up leading me to thing the intake side valve stem seals are leaking?
Well, I finally got all the parts in and got it all buttoned up yesterday and did a quick 10 mile Motoman break-in and then an oil change.
Ended up going w/ a new Wossner Piston (94.97mm since my XC-W had a Type II piston) and rings. I put all new valve shaft oil seals in, cleaned up the head and the valves and did a valve adjustment.
I gave the cylinder a quick hone w/ a flex hone and for the first time used Total Seal Quickseat Dry Film Powder
for the cylinder/rings installation. We'll see if it helps.
I used a Flex-Hone in 240 grit Aluminum Oxide, not a silicone carbide hone and did a lite pass to deglaze the cylinder.
Bike seems to pull really strong.
Today I did a 70 mile trail loop today and the bike is running strong w/ no oil consuption. I'll have to put on a few more miles before I can be realy certain everything is OK