i agree with the timing chain thats like cheap insurance lol for now on everytime i tear mine down ill change the chain i mine got wore and loose and it jumped timing bent the valves and knocked dents in the pistonHey man the head has to come off because you have to remove the valves to put the seals in. I would also recomend lapping the valves while they are out. Mine did this last fall started smoking bad during start up and reving it up. I went ahead and pulled the valve cover off the head (everything) did the valve seals and lapped the valves. I also had it bored .040 over, put in a 101mm piston, new rings. Runs great now. I also put wisco gaskets in. FYI if you do a tear down replace the timing chain as well.