I am helping a guy whose YZ400 that he had repaierd by another guy and it wont start, it turns over freely when kicking it with the decomp. lever pulled. At TDC it is then impossible to kick, two people together maybe, but otherwise impossible. Valve clearance is within spec. I noticed that the front cam chain guide is tight up against the exhaust cam, like when you take off the chain it takes a bit of force to turn it, the intake cam spins freely. Any ideas?