'81 Virago XV750 Will not crank!

Is the security light on or flashing ?
The yellow wire goes from the key switch to the neutral safety switch, then to the starter. So bypassing the neutral safety would make the starter crank the engine, but would have nothing to do with the rest of the engine.

Yes there is a starter relay in the wiring diagram.
The yellow and lite blue wire goes from the starter solenoid to the relay. There is a yellow wire from the relay to a 30amp fuse. The key switch powers thru the neutral safety switch and then powers the relay on.

There are a few safety interlocks on most Yamaha street bikes.
The starter circuit will only operate if:
the bike is in neutral and the neutral light indicates this OR
if the bike is in gear (or neutral light not showing) you must have the clutch pulled in and the sidestand must be up (there is a clutch lever switch and a sidestand switch )
The engine stop switch "kill switch" on right handlebar has to be in the RUN position to allow starter cranking.

If it died while riding, this could be a broken wire, harness plug come loose, of faulty ignition switch, you will need to use a test light to check where the power is getting to.
The ignition switches switch a couple of different contacts when you turn the key, which could explain why the neutral lights come on and nothing else.

Sounds like the starter solinoid especialy if the starter works when you jump it. I dont know if you can buy just a solinoid for that particular car, but its a cheap place to start if you can. If not you should be able to get a whole remaned starter for around a hundred bucks. Hope this helps.

if this was your problem before a new battery was installed, check the fusable link wire at the solenoid for it may have a internal break under the insulation
All cars have this inline link for fire protection to the engine

Bad solenoid i would guess. Not making a connection there. Any basic wiring and ignition switch problems should be alleviated by jumping the starter with a screwdriver. I would check the solenoid and starter brushes

There is a plug to go through the firewall above the passenger wheel well. You may have a bad clutch interlock switch (m/t) or neutral safety switch (a/c).

Kill switch works one of two ways. Either it grounds you out, killing the spark or it disconnects a circuit shuttig ignition off. So...forget the switch for a moment and wrap the two wires together, try starting, nothing ? then separate the two wires and make sure they are not touching any metal parts, try starting again.....now you have eliminated the switch as your problem.....cap off the wires and don't hook them to the switch if your bike is now running....Good luck to you friend....tim

The problem is either the starter solinoid (located on fender near battery) or you are not getting power to the "s" terminal on the starter solinoid from the ignition switch. If you follow the positive battery cable from the battery you'll follow it to the solinoid. Remove the small wire from the terminal marked "s" on the solinoid and using a screwdriver jump from "s" terminal (not the wire) to where positive battery cable connects to solinoid. (with battery connected). If starter doesn't do anything the solinoid is bad. If starter cranks then you are not getting voltage from ignition switch through "s" terminal wire.