Just back from another work trip and trying to work on the project, I'd had the carbs off last week and double checked all the settings, including float heights and pilot screws 2.25 turns out. Now the bike revs up nicely, but the revs are slow to fall back to idle, I did pinch the idle screws up quite tight before coming 2.25 turns back out. I read on another thread that if they are less than 2 turns out it can run quite lean and the revs will be slow to fall as a result. Do you think that's my problem, or could it be something else harder to diagnose like an air leak?

Do not overtighten the pilot screws, just make sure there seated before backing them out... otherwise you risk bending them and replacements are not cheap!!

Revs hanging / slow to fall back can be signs of an air-leak, maybe one of your carb rubbers are not sealing properly?

If you have some brake cleaner / other flammable stuff spray it over the rubbers while its running.. a change in rpm will indicate air-leak

which bike? some models the AF screw controls air, some fuel so further out can be leaner and that could be part of it. I have read conflicting things on this site about the AF screw for the v-fours on this forum.

Try adjusting the pilot screws one quarter turn in or out.

OK chaps thanks, Ill try both options I'll WD40 the intake rubbers while its running and tweak the pilot screws out another 1/4 turn and let you know.

Sorted thanks guys, I checked that the carbs were not leaking by spraying WD40 directly onto the top of the carb rubbers while it sat idling with no change in revs so Im happy that the carbs are sealing fine. I checked that all the slides are returning as they should by running it with the tank and air filter off, all ok. Then reset all the pilot screws to 2.5 - 2.75 turns out and it's running much better. All I need to do now is get the blowing exhaust manifold sorted (Its making a ticking noise) and the carbs balanced and it'll be ready for the first track day.

that is great to hear. so you could actually access all the screws with it on the bike? or you removed the carbs? which model V4?