I beleive my carbs need a good clean up or re jet on my 1990 nc30, talking to a fella at one of my jobs and he tells me he may still have a complete carb from a rvf 400.
my question is would it be worthwhile and would this be a straight fit to my bike?
thanks for any advice

They pretty much go straight on. Best to use rvf inlet rubbers (although you probably don't need to) and you need to use rvf throttle cables. I only run a single throttle cable (ditching the return cable).

I reckon the rvf carbs don't have the top end power of the larger vfr carbs, but that could have more to do with the actual power delivery (torque curve) between them than any actual power difference. I quite like the characteristics of the rvf carbs on my road nc30.

There's a guide to rejetting and cleaning your nc30 carbs here, it's not difficult:

viewtopic.php?f=24&t=14524&start=0

thanks for that, I already have a printout of your cleaning re jetting walkthrough ready for when I get the time to start.
Ill have to see if he still has them and how much hes willing to let me have them for.
cheers.