New pilot jets arrived today. Fitted the 20's and as soon as I fired the bike up I knew it was running 100% better.
Thanks everyone. It just goes to show how sometimes the simple things are the easiest to overlook.
The only slight problem now is the tickover. It ticks over at about 1500 - 2000 rmp. As soon as I adjust it down and ride the bike it goes back up again. If I rev the bike at standstill it then drops back down to 1000rpm. I'm guessing this is just the mixture screws needing tweaked (I just set them all to 1 and 1/2 turns out) or the carbs needing balanced with gauges. Apart from that the bike runs fine at all other revs / throttle openings.
See thread here:
http://www.z1ownersclub.co.uk/forum/vie ... 012#225012
John