hi, need advice. i am improving my nc30 and have a question about air filter box- is there any sense to remove plastic detail marked green in my picture? it fits in place marked blue and in my opinion reduces air flow

I have done what you are thinking to my NC30, but I run an HRC carb tray instead and some modded RVF carbs. What state of tune is the bike in, as messing with air and fuel can cause all manners of issues with the bikes running. Do not remove the little rubber flap attached to the frame spar though as your bike will definately run badly.

i have removed all details which are not necessary to track- mirriors, turn signals, rear footpegs etc. now i am thinking about- 1) exhaust; 2) fuel & air flow 3) dampner

so "green" part can be removed without any doubts?

Saveris wrote:i have removed all details which are not necessary to track- mirriors, turn signals, rear footpegs etc. now i am thinking about- 1) exhaust; 2) fuel & air flow 3) dampner

so "green" part can be removed without any doubts?

None of that is any sort of tune, just weight saving. Leave the little piece in place, fit a standard Honda air filter, get the carbs cleaned and balanced and leave it as standard until you have the other bits sorted.

To give you an idea, I have a standard motor, JHA full exhaust system (2 exhausts), HRC carb tray, RVF carbs jetted with HRC slide springs, short velocity stacks and air/fuel adjusted. Removed the piece you have shown above, K+N air filter and snorkel removed and a programmable CDI with an HRC map. I will be bringing it to the dyno to get the fueling sorted 100%.

If I didn't have any of the above I'd not cut the airbox.

Just out of curisoity viper, are you aware how much power your bike is putting out in that state of tune? I am considering doing a small amount of tuning to my bike you see, currently 100% Factory standard, and was wondering just what to expect?


As for the original point of this thread..
I always thought that that little plastic flap, above the rubbe rone, was to direct the cool air down below the Carburettors and help prevent them from overheating as a LOT of hot air gets produced under there.
Surely by removing it on its own and not doing anything else like Air trays etc, you might see problems with too much heat aorund your carburettors or even overheating in your engine, but this might be quite unlikely??

I have slightly modified that part on mine, but Ive only cut a small amount off the edge so the breather tube fits better under it and has a bit more free play in it, LOL So that doesnt really count does it?

Hamster, I've no idea what power the bike is yet as I've not been to a dyno to find that out. I've not had my bike on the dyno in about 3 years and the last time out it produced a sub 60 figure (56/57bhp or so) and I was so mad with the result that I decided not to go back to a dyno again. Since then I have learned a LOT more about NC's and how to change and set things correctly at home and have used a 'seat of the pants' dyno since then. I know my bike pulls cleanly for 1,500rpm to 16,000rpm and that's good enough for me. Now, I will be bringing my bike to a dyno operator and between us we'll do our best to eek out the most power with the best curve. Although my last horsepower figure was lower than when the bike left the factory the curve was linear with no dips in the graph, since then I have done the mods listed above so my jetting will most likely need changing and hope to have over 60 odd HP. Fingers crossed and I will update my thread after I get the dyno done.

so, if i dont tune carbs, i should not cut airbox. thanks for info.

Saveris wrote:so, if i dont tune carbs, i should not cut airbox. thanks for info.

Correct, if everything is standard, just leave it alone.

viper_biker wrote:

Saveris wrote:so, if i dont tune carbs, i should not cut airbox. thanks for info.

Correct, if everything is standard, just leave it alone.

I'd leave it well alone too...

Messing with the airbox and inlet side can cause so much ballache for no gain.

The airbox wants still air to suck up - it does not get forced in so much as you imagine. That flap is to cool the carbs as they get very hot on top of the motor out of the airflow.

CMSMJ1 wrote:

viper_biker wrote:

Saveris wrote:so, if i dont tune carbs, i should not cut airbox. thanks for info.

Correct, if everything is standard, just leave it alone.

I'd leave it well alone too...

Messing with the airbox and inlet side can cause so much ballache for no gain.

The airbox wants still air to suck up - it does not get forced in so much as you imagine. That flap is to cool the carbs as they get very hot on top of the motor out of the airflow.

God I love the smell of being correct in the morning. LOL