So.. I was going through my Yamaha book and fixing up my bike. I came across IDLE SPEED.. hmm. I always went by ear and never had a problem. I installed a tach meter and I have been idleing at 800 or 1000 RPM. Now the book says to idle the bike at 1900-2000 r/min. Thats nuts! I thought so too! So I tried my best.. the bike was nearly maxed out on the idle speed control and the throttle free play was maxed. The bike is a 2012 YZ450F by the way.. brand new.. maybe 50 hours... never ever had a problem. So I checked my valves and I cleaned up my air filter all nice.. Got it back running, but could not reach 1900. Im still boggled, thats waaaay to high. But whatever.. I got it up to idle at 1400. And it just didnt feel right to me, but I rode it and man she ripped. For about 10 mins... then I heard a loud ass noise, as if like the header exhaust pipe came loose or something.. you know what loud gwaaaa sound, aswell as this knock sound. Sounds like its comming front the cylinder head. I shut it off.. looked at the case and I didnt see any cracks or oil leaks.. but now she will not start.. and the kickstart is not smooth.. it has a jagged like feel.. but there is still compression. Any ideas??? Im so pissed... I cant believe this crap. UPDATE--- I got the cams off... and she wont even crank now.. its seized right up. She had to have gotten too hot and seized. I'm gonna take the head off and see if the piston will move.