I previously had had a motor fully rebuilt on a 2013 Yfz450r by Miller. Bottom end and top end. I got my motor back and it would barely even start, had to crank it over forever! And then finally my valves went... So I sent it back, ended up having to put new valves in it. New rings and he did some more head work with epoxy. Got the motor back and it still started super hard! My buddy and I took the valve cover off and after some research found that Miller put it out of time by one tooth, he did that twice! I believe that is what caused my valves to go bad. I had him put hot cams in the bike but he doesn't seem to of known how to time it. As I just got off the phone with him trying to inform him he was off the tooth he claims "usually when I do the timing on the dual cams I look through the case for the timing mark and DO NOT look at the timing marks on the cams". And was convinced he was still right and I was wrong even though it runs great now, and have good throttle response, while before I didn't. Well two gurus figured out a "professional" builders mistake that he did twice. Just wanted to inform everyone about this.