My 2001 Yamaha warrior yfm 350 makes a loud ticking noise coming from the motor, what is wrong with it????

Had the same thing on my 350 the adjustment screw for the valves had backed out had to readjust them and replace lock nuts

Valve train .Take off cam sprocket cover and check timing chain for play.Do to tight springs and steep lift cam you will get backlash(ticking) from a lose chain regardless of tappet adjustment.If it is back firing more than normal you may want to overhaul the head and replace rings.as well as timing chain.

If it is not a valve rocker arm, You may have a compression leak at the head. Soap bubble test the head gast while it is running. Rocker arm clearance can only be physically chk'd with a feeler gauge. Good Luc)Ned_

Possibly a bad lifter or a valve lash adjustment needs to be performed.