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Cam Chain Skip?

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Hey guys, picked up an 06 kx250f in june of this summer and it is my first four stroke bike. i came off of an old cr250 that i knew like the back of my hand but since i have been getting a bit more serious into racing i decided to jump to what i thought was a more competitive bike and assumed i could handle the maintenance...well i may have been wrong. i was told that it had a new oversized piston and bored out cylinder installed at the beginning of this riding season, and was told nothing about the head so i assume everything is stock up there. Checked the valves about a month after getting it (I know should have done that right away) and the intake valves were right on the tightest allowable clearance so i reshimmed them to sit in the middle of the specified clearances. the right exhaust valve was almost perfect and the left one was a couple hundreths on the good side of the tightest allowable clearance so i left that one. Fast forward to last weekend with 4 hours on bike since that valve adjustment. Was practicing for race and all went well until when i got back to the truck i heard a soft tick tick that i never heard before. i figured it was the left exhaust valve that i didn't shim last time and it was on the tight side. I thought it would be ok to just do my two last races of the season then do the valves again (I know i'm an idiot:bonk:) Made it around half way around the track first race and bike shut off. Instantly I knew i messed up the motor cause i couldn't have stalled it so i pushed kick starter by hand after everyone went by. As it turned over it sounded a little like a rattling. I actually thought i broke my cam or something. I tried pushing kicker down again and it wouldn't budge. I get the bike home and take off the valve cover to find the chain skipped about 5 teeth on each cam. (I knew this because when i first did my valves i put marks on the cam and chain with sharpie once the motor was at tdc to make sure cam was in same spot once i reinstalled it) Then i set each cam up with the marks on the chain and tried turning motor over by flywheel bolt and it wouldn't turn. i noticed that the motor wasn't at tdc by the marks on the flywheel even though the marks on the chain and cam were now lined up and marks on cam gear lined up with top of head. I assume this means that not only did chain jump on cam but i assume it jumped on the crank now too. So does anyone know why this would happen? Worn out chain? Worn out gears as well? I think the cct is still good because it still puts good amount of tension on chain. I could still turn the cams over once the chain was off and motor was near BDC so im hoping the valves will still be ok too. I know I wrote a book but i wanted to be as clear as possible so someone more experienced could lead me in the right direction of what i should do next. I'm a poor college student so i was planning on just replacing the cam chain and getting everything lined up and seeing what happens. Is this the route everyone else would go? Any help will be much appreciated:worthy:.

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