The bike I am working on is a 2006 CRF450R. I have never checked the valves on any bike before. I can just about do anything else on a bike. I went ahead and bought the HOT CAMS shim kit, appropriate feeler gauges and I already have a micrometer. I put the motor in top dead center and proceeded check intake valves and they look to be in spec at .005 and .006. But the exhaust valves are wayyyy tight at .003 for both exhaust valves. This is only about 10-15 hours since the last adjustment. At the last adjustment, the mechanic told me the exhaust very tight and intakes were almost perfect. Why are the exhaust valves tightening up so much? Only engine work that has been done is full exhaust, ported head and SS valves.