Flat Spot

[Dcock]

Right so after blasting it half way back from poole bike night tonight my 1998 fzs600 developed a problem. As i was trying to blast it past my mates fz1 my bike lost power and now will not rev past 7k unless i hold the throttle back for a good 5 seconds and then finally revs past it but with very little power. It feels liek a very bad flat spot. Also it seems to happen lower down the rev range if i'm in the lower gears. I feels as if it looses power at the point when the engine used to start pulling hard. I'm wondering whether it's running lean as i had the fan come on for the first time today also the carb rubbers are cracked, but i sprayed wd40 on them and the idle did not change.

Any ideas?

Thanks, Dan.