The cam has a ball bearing on each end if they were damaged you would hear a roar from the cyl head. you should try to keep the valve clerance's as close as possable whether you run them loose or tight (both ex the same & both inlet the same) check the valve and ign timing & A/F ratio (fuel map). failing that i would pull the head off and check in side for damage before it goes BANG! it will cost you lots then.