Hey guys, first post on TT. I've been reading info on this site for a while, so figured I should finally join! I've got a 2008 Yamaha YZ450f. I got it from a buddy. He was riding it (he said) at low speeds when it died on him. He started it up, died again, then could no longer get it started. Turns out it jumped time. He pulled it apart 3 years ago, and it sat that way until I bought it a couple weeks ago. The head, valves, and piston looked good with no indication that I saw of contact between valves and piston. To check to make sure the valves were seating, I put an old plug in the head, flipped it upside down, pooled WD-40 in the chamber to submerge the 5 valve faces, and let it sit for 24 hours. I didn't see any wd40 that had seeped past the valves into the ports, so assumed they were fine. I bought a new head gasket, cam chain, tensioner, and gasket. Got everything put on the bike. Head is torqued down. I went to check the valve clearances, and holy ish they are loose! I'm talking .5mm on the exhaust side, and probably .2 on intake side (I will get actual numbers for each hopefully tomorrow, these are just ballpark what I remember off the top of my head). I thought they usually tightened up when wearing. My question- is it possible that maybe the valves did hit the piston, and compressed the valve maybe? Scary thought, but other than someone not knowing what the hell they were doing when they adjusted valves, I dont know how they could be this loose otherwise. The bike has I'd say 75-100 hours on it. I'm considering starting the bike, since head gasket is already not re-usable since torqued down if I pull the head off again anyway, letting it run a little, and re-checking clearances. Is this ok? Any advice/input is greatly appreciated!!! Thanks in advance.