Habit of mine is to always start bike with clutch pulled in, even when I know I am in neutral.
Use a rucksack otherwise if you fall off the ambulance people will think your Liver has shot out of your mouth
Noggy, it could be the ignition switch which has 2 wires that supply an earth to the ECU, without this earth the ECU will not work. The earth is taken from the neutral switch and/or the side stand switch up through the ignition switch and back to the ECU..The fact the engine turns over on the starter rules out the side stand switch as it also supplies the earth for the starter circuit.A few questions to narrow it downDoes it happen with the bike in neutral?Does the neutral light work?Does the neutral light still work, when this happens?Does it happen with the bike in gear side stand up and the clutch pulled in?Check the wiring from the ignition switch to ensure there is no corrosion in the plug under the tank. It does not take much corrosion to cause the problem. Has anyone on the forum taken one of these switches apart? (I have not seen the inside of one) as it may have a resistor like the Suzukis have to prevent hot wiring. If not you could bypass it the next time it happens and if it starts change the switch.How proficient are you in using a meter? you could test the wires of this circuit to ensure good continuity.
The Crank and cylinder sensor plugs should be checked also as corrosion there could cause the symptoms you describe.When I was checking for a similar problem some time ago it was the plug for the crank sensor which was corroded.Does it happen hot, cold or anytime??
Have you replaced the clutch switch?
Great explanation I wish I understood it
Does it always start with the clutch pulled in????
NoggyThat is a different issues and more or less rules out the Ignition Switch and looks more like a wiring issue or a diode gone in the starting cut-off relay. I have seen fellows blow these when they did not know what they were doing .Might be worth while changing the Starting cut-off relay, they are used in the FZ6, FZ1, FZ8, R6 and R1 so should be common enough and cheapish.The part number is 5VK-81950-40What is the under seat code of your bike? it is probably 3C37 something or 3C3A something. This will determin if it is Local or Foreign