Timing issue, center intake valve keeps breaking off
Any ideas anyone ? I have a 2005 Rhino 660, After a complete top end engine rebuild I have had problems with the center intake valve. I have replaced it three times now. Engine runs fine after initial replacement then when i take out to riding area the valve breaks within 10-15 minutes ride time. The issue is the piston is making contact with the valve. First two times it broke I was at full throttle, this time I was at about 50% throttle when it broke. All alignment marks are correct for the cam gear, cam and decompresion springs. I just replaced the timing chain and installed NEW 700 chain tensioner on most recent rebuild. I'm at a loss for what going on. The cam is a Hot cam installed by a previous owner. I have had Weller Racing look at the cam, head and valves and they have supplied the parts and done the machine work. Is it possible that the pin inside the cam that contact the center valve isnt working properly ? Somehow this thing is going out of timing. When I disable the motor the timing alignment marks are still correct. There is no damage to the pistion just a little mark where the valve made contact. Any ideas anyone ?