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2001 yz426 oil behind crankcase plug and wont idle properly

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Ok I have a 2001yz426 last summer it started idling really high and adjusting the idle or fuel screw wouldn't help it either idled really high or not at all, took the carb off to clean and when I removed the top cover to take the slide out I found a bunch of dirt but I didn't see any in the intake so I cleaned the carb and replaced all the rubber seals

Then I went to check the valves and when I went to remove the plug over the crank so I could turn it with a wrench to get the engine in the proper spot oil started leaking out, the bike has been sitting for a while but I don't remember oil being in there last time, do I need a new crank seal or what

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It's a dry sump system, meaning the oil supply is stored outside the crankcase area.  In a 426, it's in the frame.  If you let the bike sit as much as a week, it will drain out of the tank past the oil pump, and into the crankcase.  To return things to normal, start the engine and let it run for about a minute. The oil will be returned to the tank, after which you can let it cool and proceed with the valve inspection.

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Ok I got everything apart and checked the valves both exhaust valves where at .007 the low side to be in spec is .0079 so I have to shim those, the intake is where it gets bad possibly, both outside valves are .004 right at the lowend of spec but the middle valve I cant get anything to fit the smallest feeler gauge I have is .0015 and that won't go but I cant tell if its getting hung up on the cylinder head casting or the valve is just zeroed out I tried trimming a .002 shim down narrower and it didn't fit so I think the center valve has no clearance 

Is it normal for one to be that far off compared to the other two? 

And I didn't trim the .0015 shim down narrower because its not mine and I dont want to go cutting up someone's feeler gauge 

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The center valve usually wears faster because all the heavy stuff in the intake stream, like fuel, oil, and, dare we say, dirt, tends to run down the center port instead of turning outward at high speed.  Since this engine has titanium valves, the rule is that whenever you need a shim more than .10mm (.004") smaller than what the valve originally had when new, you probably need a new valve in that port.  Because of the heat expansion dynamics of the head and the valves, it's actually possible for the valve to wear to zero clearance while running hot, then cool down and have less than zero clearance, or to put it differently, to be held off the seat by as much as .002" or more.

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