My bike runs and the indicators work but everything else is dead.Any ideas please?
I've checked all the fuses and they're ok and so is the main earth.
I've taken out each fuse in turn and tried the lights/horn and checked to see if that sorts the problem.
I've checked all the connector blocks are tight and tried wobbling the wiring whilst I've got my finger on the horn button, in case there's a dodgy wire. It's worked before.
I've sprayed the ignition switch with wd40 and still no luck.
I hate electrics!

I tried the lights again and everything worked but when I switched the ignition off and then back on again everything stopped working. I tried the lights again ten minutes later and they worked again but as soon as I turned the ignition off and on again they wouldn't work.

And I thought I had problems.

Sorry cant be of any help. Apart from telling you to check everything you've probably already checked.

Wow - that does sound like a weird one. I don't see any sensible way to attack this short of a multimeter and tackle short sections of the electrical diagram at a time. On a computer I'd say it's a thermal fault - perhaps there's something that's only working when the current heats it up a little? Maybe you have a leak to earth that's fading out as the cable warms up?

That's really clutching at straws though, and probably less than helpful to you :-/

Got to be an intermittent loose connection - and since it happens when you turn on/off I'd say it either a connection to the ignition switch or maybe the switch itself is failing.

I hate electrics too but they usually turn out to be simpler than you think. But intermittent problems are the worst.

ignition switch maybe or plug to the switch, it does have micro relays inside fuse box, starter and lights check the plug that goes into the fuse box is ok
not sure about the GPZ but some bikes have a multiplug on the starter soleniod with several live feeds usually 2 or 3, ing switch, rectifier and fuse box

I had planned on trying to sort out the electrics on the Gpz today and guess what happened moments after I got the seat and tank off it starts raining! I did manage to check the charging circuit and find out that instead of the 14.5 volts it should be putting out I've got 17.5.
I found out last week that there was a corroded wire on the ignition switch which I've now fixed and the connector on my brake light had corroded away too.
I'll get there in the end.
I can't solder the wires either they seem oxidised to me.

You are right, it turned out to be a faulty relay getting hot. I wish I'd realised that before buying a new regulator/rectifier
I'd forgotten that I'd had a similar problem last year which stopped me going to Squires. The Squires weekend is jinxed for me, apart from bike problems last year on the Saturday I had a bad stomach bug and this year I put my foot in a hole and badly sprained my ankle.

I got another relay off e bay and all of my electrics are working again but now the bike doesn't want to run properly. It starts but sometimes only fires on three cylinders or wont run off choke and if you try pulling away the engijne cuts out.
I've checked the plugs and they're black, they're usually a brownish grey,but one of the plug caps has corroded inside which obviously wont help. I'm draining the fuel and emptying the carbs to start with and I'll go from there.