Top End Rebuild, Won't Start!!!!!

[SincYZ450f]

Had a quick check of the valve clearances and 1 off the intake cams has 0 clearance it is touching!! the shim itself is in flat aswell. think i will re-shim it. How could this happen if it ran fine b4

[BC3]

If it has enough compression to where you feel it when kicking it through(auto de-compression ?) I can't believe it's a valve adjustment issue.....They might need adjustment but that shouldn't keep it from starting.....Especially since it ran good before the top end job...Check the ignition timing (Spark) and see if the plug is "WET" the answers to these checks should get you running...

[yam 3]

Had a quick check of the valve clearances and 1 off the intake cams has 0 clearance it is touching!! the shim itself is in flat aswell. think i will re-shim it. How could this happen if it ran fine b4

Same here take it out and wipe it off good and reassemble...fixed mine. Must have had a dog hair under it!?