Exhaust Valve question, 1 discolored

[bart550255]

I have 2ea z400 quads (06 and 07) and noticed one was loosing power. I have done valve jobs before so after ruling out sparkplug and intake problems I pulled the head. Looking at the valves the 2 intake and one of the exhaust valves look normal(dirty brown, no scale or residue) but the second valve had a thin powdery grey/white residue all over. I am thinking this is the one that has issues either the clearance is to little or it just isn't seating so it is leaking and/or running hot. I haven't had time to put the cam back on to measure the clearance (I know should have checked before I pulled it off) but I plan to do this tonite.

I was wondering has anyone else has seen 1 discolored valve while the rest look normal? Does this sound reasonable for a single cylinder 4 valve engine?

If so the fix is lap the valves and or adjust the valve clearance.

thanks for any advice.

:) :)

[bobizzle]

i have seen some cases of this on lawn mover engines, primarily on the exhaust valve. which valve is it on and do you have pictures?

[bart550255]

The 1 doscolored valve is one of the 2 exhaust valves (right side). No pictures since as soon as I removed the head and the valve seated (presuming the valve spacer was to thick causing it to not completely close/seat) the oily residue on the head began to wick across the face of the valve and now it looks just like the other 3 valves (dirty brown). This action further confirms my suspicion that the valve spacer was to thick. I checked for valve leak last night with cams off and no leak so tonite i will record the valve spacer thickness (for each valve) reinstall the cams anc check clearance. If I find not enough clearance on the 1 exhaust valve then that ends the troubleshooting for me I can pick up a new valve spacer from the dealer and put my engine back together.

[bobizzle]

is the one that is discolored not seated right?

[bart550255]

Please....no more stupid questions

thanks

[bobizzle]

fosho then, just tryin to help