What makes a Yamaha virago 920cc starter kick in and out when starting?

you have a short out in your wiring maybe
try by passing the switch
ie take the wires off and connect them up
if it still does not work disconnect the wires

chec connections in ignition area and make sure batt has 12.6volts-that motor has alotta horses--carb probly needs overhaul or choke maintenance

I would take them off and make sure there is no mung in there. Also on the XV's make sure the vent tubes are clear. I've had problems with insects building nests in the carb vent tubes that go through the frame.

change the starter, pinion gear on starter is worn out if your lucky if not lucky the gear it connects to is worn out= split the cases to replace not easy to do

first off it is not a bendix starter on these bikes! there are several fixes for these starters,,, but most important is that the bike s in tune! if it has running problems with carburetor's they are hard to start anyway..

the early virago's had a gear that slides out and engages into the flywheel, there is a drag clip that forces it to slide and wears out, also if the edges of that gear round off makes it worse too

Sounds like:
A: The starter clutch is slipping and not letting the starter engage the crankshaft
B. The carbs need to be cleaned. If ti has sat unused for more than 30 days, the pilot jets are clogged up causing it to stall (off choke) and be sluggish on acceleration off idle.