Ok, what condition is the bike in, has it been sitting for a long time, has the problem suddenly appeared, has the bike been worked on recently ? Do you have a manual ?
Are the throttle cables in good condition, and sdjusted correctly, 3-4 mm at the adjuster ot the carbs end.
Are there any leaks on the carb rubbers between the carbs and the cylinder head, spraying WD40 on these will speed up the tickover if there are any leaks..
Try pressing down on the tops of the carbs.
Is the throttle action smooth indicating that the slides are OK.
Take the tank off and see if anything is mechanically stopping the carb slides dropping.
There is another adjuster on the carb linkage just below the "pull" cable this is eccentric and there should be a 2-3 mm gap present between it and the throttle lever, this could hold the slides open. (it's called Overcross stop adjustemnt on the manual) When your cables are adjusted properly by firmly closing the throttle from the tick over position it will slow the tickover.
Look at the slide stem on top of the carb you should only see about 1 - 2 mm of shiny stem.
What are the pilot air screw set on, screw them all the way in (to contact only, don't force them) then screw them out 1 1/4 turns
Cheers
Den