Bike has new intake valves after having the chain jump a bunch of teeth on the intake cam and valves hitting the piston. I get the bike together, starts 3rd kick, and it rips. It sounded very crisp and strong while riding it for 3 hours, so I thought it was safe to take it out on the trail. I trail ride it for another two hours, then stop the bike to take a break. When I start the bike back up, there is a HORRRID tickslaptickslap sound from the engine. I shut it off imediately, and the kickstarter would not buldge. Great, the piston bent the valves again. I wasnt going to push this pig home, so I pulled the valve cover off on the side of the trail (thank god for brining tools), and sure enough its off timing. I fix the timing, and to my luck it has the same compression as before. Starts right up, and I thought it be too good to be true. When I stop and start the motor again, it makes the same terrible noise as before. When I turned the motor off and kicked it over with the decomp pulled in a few times, it starts right up. Weird, but I rode it home anyway. So I pull off the valve cover again, and its off timing. Thats even weirder, how did it run with a tooth or two off time on the intake side? It still has full compression when I timed it back right. I'm guessing its the timing chains fault becuase it does look a tad loose and probally hasnt been replaced in 5 years. The tensioner is working fine too.