i noticed gum dripping onto my exhaust pipe recently. i did a quick check and realised that it was coming from a black box with wires attached to it (left rear fairing above the exhaust). im assuming the black box is my CDI. what is the next step i should take?

hmm I'm not quite sure where the CDI is on these bikes as I've never touched mine but I think the black box you're talking about is the regulator/rectifier. It clips onto a rubber mount on the sub frame above the exhaust under the rear fairing as you have described.

It is a common problem for these to fail on NC's.

Yes, the reg / rec is on that side of the subframe as well but the cdi is also a little further back, closer to the end of the end can.

I personally have no idea why "gum" would be dripping from the cdi!
If it was my bike & i noticed that, i would be getting it off & opened up to find out wtf is going on.
If the bike is still running then, it doesnt sounds like the end of the world.

The Regulator is the small square one closest to your heel it bolts to the frame and the CDI is the bigger rectangular one hanging in a rubber further to the rear.

If the gum is dripping then its on the way out. You should replace it with a new version one with fins to cool itself( suppose yours is still the old original ).
If you keep riding it your moto will fry the battery and in turn you would probably need to change the charging coil and cdi to as that will be getting fried as well (if you end up getting a new battery with out fixing the regulator)

ah i will take a picture and post it to let you guys confirm whether its the cdi or rectifier. thanks!

reg / rec has just 1 plug going into it from the underside & the cdi on an rvf, has 2 sections of loom plugged into it from the left hand side - plus the cdi is about 3 or 4 times the size of the reg / rec.

cdi - http://cgi.ebay.co.uk/Honda-RVF-400-CDI ... 27b3f4d98b

stock reg/rec (i think, if not it's very similar) http://cgi.ebay.co.uk/NEW-RVF400-RVF-40 ... 1e5e5c9904

hmmm im pretty sure its the CDI according to the pictures you posted...

Dude I'm pretty sure whatever is melting is not good...

Sounds like your charging system is eating itself alive to me.

RVF parts manual can be found here (4.4Mb):
http://www.akhara.com/nc30/nc30manuals/ ... Manual.pdf

If it is the CDI, then it might be fried and the resin on the PCB has melted - not sure how it would find its way onto your exhaust though?