Why is my Kawasaki VN800 Classic not starting?

I’ve had a Kawasaki VN800 Classic for over 15 months now, and it had been running beautifully every day until a few months ago when it would just not start on the button, clicking loudly instead. I checked the battery was good (it still is), so then thought it was the starter, so I took it off and checked it was working (it was) and put it back on. The bike fired up, problem solved. Only now it’s playing up again.
Now it will start first time, but then won’t fire up if I try to start it again – for example I will ride it to work fine, come to go out for lunch and it won’t start. Come to leave for the day and it might not start for 10-15 minutes, just making a beefy “click” sound, until it will just fire up. Get it home and it won’t start again.
Baggat, MCN forums

This sounds like your starter solenoid is sticking. It’s basically a big switch that engages to transfer battery power to the starter motor when you press the go button. Normally the piece of metal inside goes from one contact to another, makes the circuit, and the starter turns. But when it fails it doesn’t switch properly and all you hear is the “big click”. You can bypass it to start the bike by using a rubber-handled screwdriver (stops you getting an electric shock) to join the two contacts and make the circuit. Next time the problem happens use the screwdriver trick, and if the bike starts, then replace the solenoid.

If it’s not a battery or electrical problem it could be a hydraulic locking problem, with you saying it starts sometimes but when it won’t there’s a “beefy” click? If there is dirt, water or debris in the carb this could be holding the float needle valve open slightly, allowing fuel into one or both of the cylinders. As you cannot compress a liquid (petrol) then this will lock the cylinder coming up to compression. If you find it won’t start again, try putting it in second gear with the ignition off and rock it back and forth until you hear it go over one compression stroke. Then take it out of gear and try starting as per normal. If it is this problem also check the diaphragm fuel tap, as this also can cause this hydraulic problem if fuel leaks past the closed tap directly into the inlet.