put a 12.5 piston in predator and did every thing by the book. started right away and runs smooth , except for a loud clicking noise, any ideas. the only thing i didnt do was check the vavle clearances before i put the vavle cover on. since you just remove and do not change anything with the whole head vavle assy. could this be the problem? or could the vavles be hitting the piston. wiseco and hpd said their should be plenty of relief with the new piston, that it should be fine with stock cams and springs. any ideas. please advise. thanks

 

did you tighten the chain timing? look around the bike for other things than motor noise! drive chain, wheels!