check the dizzy, make sure the trigger window has 4 windows on it, not 1. also disconnect plug on main pump and turn key 1 click, make sure in-tank pump primes. when you say you checked the timing, which marks were you using? best to use the flywheel punch mark as i have seen crank pullys be out as much as 90degrees before. also are you checkign where the rotor arm is pointing rather than the intermediate shaft, as the dizzy can be way off the int shaft marks. i never even look at int shaft, just concentrate on where the dizzy is pointing. also, check the cam lobes on #1 point are pointing up and diagonally away from each other like this when the cam sprocket is lined up:
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if not could be keyway is sheared or sprocket is fitted backwards