Question jetting NC30

atac · Post by **atac** » Sat Mar 12, 2011 4:27 pm

I have a question about it. Why (here in forum) is prefered to jet the front cyl leaner then the rear cylinder, like 118/120?
In the OE Hondamanuals (akhara) always the front cyl are richer then the rear one, like 122/120.
i have a german import (its still totally stock), i cleaned today carb and its funny. 120f/120r, Needles J3UF front, J3Ug rear. and its not common with the OEM Manual, because here is provided 122/120.
But on spare part list on CMSNL this jetting is exactly the same on the german model like mine!! all other Models Europe (Austria/ France UK use 122/120 and different needles und fuel tubes and slides!
My slides are a type with 2 holes.
Are ther so many types of NC30 carbs? And why you prefer to jet front leaner then rear in opposite uf the OEm Honda regarding?
thanks

Post by **Hadies** » Sat Mar 12, 2011 5:20 pm

I believe the rears get hotter so could do with being less lean.

atac · Post by **atac** » Sat Mar 12, 2011 6:38 pm

That sounds logical, but the OEM Honda manual says the opposite of that. front richer than rear cyl.
-118/120 for sportexhausts- why lean up the mixture, stock is 122/120?? Open Exhaust generally needs to richen up fuel, or i think wrong?

Post by **BillingCBR** » Sun Mar 13, 2011 1:10 pm

The above is (I believe) refering to the Japanese model bikes, 110's for the R3K, 112's for the others (Although that may be wrong, don't have a manual nearby atm)

arsey30 · Post by **arsey30** » Sun Mar 13, 2011 3:51 pm

Free flowing exhausts need richer jetting, better flowing airbox/filter even more richness.

There are 3 different approaches to front/rear jetting, and the manufacturer will carry out tests to confirm the best for that engine.
e.g richer front, richer rear, or both the same.
1 approach is that if the rear cyliner runs hotter, then richen up to help cool it.
The other approach is to weaken that cylinder if running hotter, as that will be the correct mixture.
The last approach is to run them both the same.

Dave.

Post by **Cammo** » Sun Mar 13, 2011 10:58 pm

atac wrote:In the OE Honda manuals (akhara) always the front cyl are richer then the rear one, like 122/120.

I've never heard of the front cylinders being jetted richer then the rears on standard nc30's. Standard for the L-N Jap model bikes is 115 front, 118 rear.

The Euro bikes are jetted richer than the Jap bikes, maybe because of the colder weather.

atac · Post by **atac** » Mon Mar 14, 2011 7:59 am

Page 1-6, front richer than rear. OEM Honda.

http://www.akhara.com/nc30/nc30manuals/ ... 0R_C01.pdf

arsey30 · Post by **arsey30** » Mon Mar 14, 2011 8:34 am

Honda workshop manual, spec for uk nc30. FR 122 RR 120
RC30 Instruction manual FR 115 RR 112.

Dave.

Post by **Cammo** » Mon Mar 14, 2011 10:27 pm

Wow, never seen that, weird...

Question jetting NC30

Question jetting NC30

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