250MC has gone LEAN!

[GasMCAndy]

I am figuring crankcase leak? Without substantial weather or altitude changes the 2003 250MC has REALLY gone lean. Progressively loosing power on Top End. Bogging on the main with slight pinging at about 3/4 throttle. Low throttle seems great on power...

35 hours on new top end
PWK 38 RB modified carb. Cleaned thoroughly-no change. Floats good at 16mm. 45Pilot/188 main as I've been riding this winter. CEK moved today from usual 4th to 5th to get ANY color on new plug. Sea Level/50F southeastern Washington State.
Good fuel filter
15 rides on new Boysen Reeds and gaskets. Properly torqued.
I sprayed Carb cleaner around the cylinder base, reeds, case seams at idle- no idle change.

Thanks for your replies! -Andy