What sort of air box setup are you running with the 115 sized jets?

Fuelling requirements on nc30's are mostly related to induction setup on these bikes rather than the exhaust. With a 3/4 system and standard air box and filter you shoul be running about 120 size main jets. Once you start messing with air box mods the fuelling requirements go up considerably. A standard air box and filter will give best power and delivery unless you go the full hog HRC open carb setup, modding the air box just isn't worth the headaches sometimes.

If its running really lean it will usually misfire and refuse to rev out at high revs and high loads ( high gears). Rich and it will usually pull through to redline with reduced power.

I initially ran it with a stock setup, as a precaution. Then, believing the bike to be running rich, I ran it with the cut airbox that it had originally come with (snorkel cut out and the hole opened up a bit). Both were about as bad as each other. The bike didn't really feel like it was misfiring or surging... just pulling weakly all the way through and not wanting to rev all the way out.

I've got 118s, 120s and 122s on order to jet to your guide with the stock airbox (thank you again, btw. It's already been invaluable for getting the carbs out and knowing what's what). I did search around for a guide for running a pseudo HRC box, because I'm uncomfortable running competely filterless, but as you say, looks like it's stock or whole hog.

TBH, I don't mind if I'm a little down on power on my mates' RGVs... it'll force me to ride better to beat them :D. But at the moment, power alone is losing me 2.5 seconds or more, and I'm not good enough to overcome that with skill.


[Update]
I think I've traced the problem (or the primary symptom, at least). I may only be running on 3. Most of the plugs look good, if a little oily on the threads (I have no idea what would cause this). But one of the front plugs is much darker.
Typical:

Front left:


So now I have to work out what's causing this. I guess I'll ferret around the site for how to diagnose spark issues. The only thing is that I don't know if the bike has previously been run overrich (the other plugs don't suggest this) and that plug was fouled already, or if it's happened recently.

1 more quick question: I notice a lot of reference to 'killing' plugs by flooding. Are they genuinely wrecked to the point where you can't clean them up? Or does the 400gb community just not advocate cleaning plugs and reusing them? Is the plug not going to work if I take to it with fuel and a toothbrush and put it back in?

It's the point they don't work again, nothing against cleaning and re-using if possible.. were not selling plugs so no money is being made.

Since that plug is so black it looks like it's over-fuelling on that carb.. it'd be wet if it wasn't firing.

Clean it up with a wire-brush and see how it runs, if it's still firing what color does it goto?

Maybe float heights wrong / it's overflowing fuel in the cylinder, jets etc.

Neosophist wrote:It's the point they don't work again, nothing against cleaning and re-using if possible.. were not selling plugs so no money is being made.

Haha, touche.

It's just that I'd never really heard of plugs dying before. I'll try new plugs (among other things).