My nc30 is running a standard exhaust system but i have an aftermarket end can. Stock air filter cut and foam inserted.

My bike is a K model so its recommended 110 Front and Rear jets which will definately run lean.

Will running 122 Front and 120 Rear jets make it over fuel?

Or would 115F & 118R be the better option?

I know getting it dyno'd would be the best option but i cant afford it at the mo as ive loads of other spending to do on the bike.

Thanks.

Go with 115f/118r as they are rich from the factory so it might run a bit better with a free-flowing can. Get the carbs balanced and float height sorted while you're at it too, that'll help you a lot. 120/122 is too much for just a can. Also, I'd go back to a standard filter too.

What he said

Excellent advice thanks.

One more thing, I have a half system which im gonna put on the bike down the line, as it needs some welding, would 120/122 be better to use when i put the half system on?

Again, I'd say that's too big. 118/120 would be a good start but ultimately a dyno set-up to ensure the fueling is correct would be the best option.

I think stickshift has a lot of experience with foam filters and jets, i'm sure he'll prob reply when he reads this.

Neosophist wrote:I think stickshift has a lot of experience with foam filters and jets, i'm sure he'll prob reply when he reads this.

Thanks Neo, but I don't have much knowledge of foam filters, those bikes I see with them I try to persuade to go back to a stock filter as jet sizes for this setup is relatively well known.

I've tried to jet a few dudes bikes who have foam filters, and it seems there's too much difference in the flow of different sorts of foams to give a jet suggestion.


Sam: How does it run know? Does it pull to redline cleanly in 2nd gear? 3rd gear? If you use a standard air filter you wouldn't go far wrong using 118/120 jets.

Foam filters usually require 128+, but there's so much difference between them that a dyno is usually needed to get the main jets right. You won't gain anything by running a foam filter, just less rideability since it's hard to jet for the transition between needle and main jet on stockish setup.

Stickshift wrote:

Neosophist wrote: Sam: How does it run know? Does it pull to redline cleanly in 2nd gear? 3rd gear? If you use a standard air filter you wouldn't go far wrong using 118/120 jets.

I havent had it running as i stopped using it 6 months ago and its getting serviced so i can start riding it again.