So.... It was running, then I left it for a few months, now it's not.
I'm pretty sure it is electrical. 12 volts up until the ignition then nothing from it, both coil packs are showing 12 volts, power is going to the solenoid but, the single wire from the solenoid is not showing anything. The kill switch works, but, the starter button doesn't. All the connections have been cleaned and appear okay.
Crossing the solenoid with a screwdriver the bike tries to fire, but, doesn't start.
I am stumped, any help will be greatly appreciated!

Recharge the battery and then put a volt meter across the terminals you should get about 14volts.
You could try putting jump leads on the battery and then try starting it.

Does the starter solenoid click when you press the starter button? Ive spotted replacement FZR solenoids pretty cheap on ebay (£14ish).

I get the feeling that these bikes are reluctant starters with a lower than optimum battery voltages - though someone else will have to confirm. Mine was really unhappy with a terminal voltage of approx 12V. The 12V will always drop as soon as you add any load and a starter motor is a pretty big load

Have you tried starting it with the battery hooked up to a car? Then check your sparkplugs are giving a spark - with new ones fitted mine still didnt look great, even with the battery connected to my car (Though it would actually start at that point)

The other obvious thing is to empty the fuel out of the tank (and carbs too if possible) and replace it with fresh petrol. Old petrol is a bit of a git for preventing starting

HTH

Generally the bikes need a charged battery and clean carbs, after that it gets a bit more involved. Its best to start the basics and work through though and ATM weve been told the bike hasn't been used for a while and it could be electrics