I recently bought a 1985 atc 250sx and it did not run because it had a broken exhaust valve which also bent the intake valve. I took the engine off and replaced the valves and also the piston rings and the engine was running great but later the same day I had it running I went to kickstart it and it didn't want to start and kinda of sputtered and then it wouldn't turn over. I tore it down again and found it jumped timing and bent the exhaust valve. Is there anything else that would have caused that except a bad chain tensioner? And is there any rebuild kits for the tensioners or adjustments or do you just have to buy a new one? I have the complete honda manual but it just shows you tear down and reassembly but doesn't really go into it much. I also called honda and they want like $85 for a new one. Is there any good aftermarket units that aren't so expensive. Any info or help will be greatly appreciated. Thanks.