i have an 04 kx250f. it sucked the left intake valve up into the head. i took the head had it inspected. the shop said it only needed the left intake valve done, and they replaced it for me and did a seat grind. i replace the rings on the piston and put the head back on the bike & cranked it up. there was a noticible tapping noise so i shut the bike off immediately. i tore back into the head and the left intake vavle was at zero clearance. i then reshimmed it to get it back into tolerance. now the bike will not start, and there is a noticeable hissing noise coming from the engine when i kick the bike over...it sounds like it is losing compression, but not through the head... what gives?