Originally Posted by Jofr

I got it fixed today by changing the oil to JASO certified oil. After the test I did yesterday I couldn't think of any other reason than that the clutch plates had swolen up or were sticking due to wrong oil. I never had problems with that oil before in other bikes but perhaps the manufacturer has changed it in recent months or the XT 660's plates are a bit more sensitive Either way it's fixed thanks for the help!

I do find that it seems the point from engagement to disengagement is very short making it hard to move the bike foreward with clutch while idling - it stalls easily without adding gas. Could also be that the idle rpm is a bit low though.