Sounds like a problem with the either the clutch, push rods and ball, or the adjustment mechanism thats on your pressure plate. How old is your clutch ? When I rebuilt my motor I didn't put my clutch plates on in the right order at first, once I corrected that problem I had to use the adjuster mechanism on the pressure plate to set the right length of the push rod. I'd drain your tranny oil, take off the right side/clutch cover and remove the pressure plate. Then lean your quad over to the right side to get the ball and the inner push rod out. Reinstall the first push rod, then the little ball, then the pushrod #2 and mess with the adjuster in the pressure plate by loosening the nut and screwing the pushrod in or out with a Phillips screw driver and keep messing with your clutch and shifter to see if the the clutch is engaging and shifting into gear. Also measure your clutch plates and pressure plates and compare the measurements with the specs in the manual to make sure you don't need a new clutch ( clutch and pressure plates ).