Hey guys I’m new to this forum. I just recently picked up a 01 400ex and it ran good but had a bad tick to it. So I pulled the head off and one cam lobe and rocker arm was worn. I found a head and cam off of a 99 and installed it. I put the different cam in with the lobes facing down, timing mark lined up, and both lines on the cam gear lined up on the block I then adjusted the valves and put it all back together. it will not start unless I am pushing on the throttle and when it does start it revs up and down and will not stay running unless I stay on the gas. I wouldn’t think a carb problem since it ran fine before the cam and head change. Could the timing be off a tooth and still run? I’m just real stuck and any help would be appreciated.