i think castrol meets the requirements specified by Kawasawki but i better check i guess
if the valves were the problem wouldnt there be some sign maybe smoking or oil burning

 

Just a thought: The 650 manual says to screw the dipstick all the way in when checking the oil level. Most bike you don't screw the dipstick in. Are you in fact screwing the dipstick in when checking the level? If not you may be overfilling it.

 

i did read that in the manual because i have heard some of the other fellas say they dont have to screw the dip stick in so when i do check i do know to screw it in
thanks for the suggestion