I just put a stage one hotcam for a 03 yz450 into my 99yz400 for the DCM, took it out this weekend and after some fairly easy riding the exacust cams slipped forward a tooth and it wouldnt run. Fixed it at the camp site and it fired right back up. After about another 45 mins of riding it slipped agian... I didnt replace the cam chain while putting in the new cam being cheap so i am going to do that. Is there any other reason the cam would be slipping? The cam chain tensioner seems ok. Do the cam chain guides wear out?