NC30 carby jetting - DIY guide

Forum rules
Please can you post items for sale or wanted in the correct For Sale section. Items / bikes for sale here will be removed without warning. Reasons for this are in the FAQ. Thanks
Post Reply
User avatar
BB_158
Site Supporter
Site Supporter
Reactions:
Posts: 256
Joined: Mon Jul 30, 2012 1:16 pm
Bike owned: is half tidy
Location: S Wales
Re: NC30 carby jetting - DIY guide

Post by BB_158 » Sat Mar 30, 2013 2:07 am

Cammo, I wouldn't have attempted taking carbs apart without this guide, I really can't thank you enough!

Bit of a hiccup as couldn't get airbox baseplate off, a previous numpty had fecked the screw heads and they are not very accessable ARRRRGH!, but once past this all went smoothly and to my delight I found the wrong emulation tubes in 2 of the carbs & one was partially blocked. Cleaned & swapped, rest checked, extra washers addded & diapham slides drilled all as recommended.

Gone are the hunting tickover and megga low end flat spot, now pulling strong across entire rev range, its a totally different bike!!!! Chuffed to beans :)

What also makes me smile is that I know that if they were visible, I can now see my face in the diapham covers SHINEY SHINEY! ;)

Cheers, Mike

User avatar
Cammo
Site Supporter
Site Supporter
Reactions:
Posts: 5524
Joined: Thu May 01, 2008 12:35 am
Bike owned: NC30
Location: Melbourne, Australia
Re: NC30 carby jetting - DIY guide

Post by Cammo » Sun Mar 31, 2013 12:17 am

Glad to hear it Mike.

It's satisfying to do the work yourself - you learn more about your bike and save the cost of getting a garage to do it.
"It's just a ride" Bill Hicks

EvanTate
Settled in member
Reactions:
Posts: 56
Joined: Thu Oct 25, 2012 12:17 pm
Bike owned: VFR400 NC24
Location: Cape Town, South Africa
Re: NC30 carby jetting - DIY guide

Post by EvanTate » Tue Apr 09, 2013 5:17 pm

Jac-al wrote:hey guys ive checked everything and am still having the same problems as per this post viewtopic.php?f=24&t=40192. thought it was the reg/rec, but now im thinkin the same think i did at first. im sure its running lean cause the jets r too small, tp recap i got an end can and done the carb mods from here with 110 jets all round, im in S.A where its hot, surely the jets r too small, it ran strong with the std pipe with 115/118
I'm in CPT running 120 main jets all round. Also got a very free flowing exhaust (guy before me put a scrambler silencer box with removed muffler on). Had no issues until my motor ran a bearing now I'm battling to get my carbs set up correctly again after they were laying around for 6 months.

EvanTate
Settled in member
Reactions:
Posts: 56
Joined: Thu Oct 25, 2012 12:17 pm
Bike owned: VFR400 NC24
Location: Cape Town, South Africa
Re: NC30 carby jetting - DIY guide

Post by EvanTate » Tue Apr 09, 2013 5:24 pm

Jac-al wrote:
EvanTate wrote:Carbs were in for two weeks to be done and after 2000 rand I got them back and put them on and bike still wouldn't start nevermind run.

This is what I found after stripping the carbs myself tonight:

5-hole emulsion tubes in front carbs
4-hole emulsion tubes in rear carbs
Emulsion tubes mostly blocked
Main jets clear surprisingly (115 all round)
Pilot jets won't come out

Not to even get started on the butterfly syncs and choke issues... :evil:


Just some input if possible before going to get spares tomorrow. My bike's exhaust (NC24) has had it's baffle removed and I do not have the money to buy a new silencer atm. So what size jets should I put in? Main and pilot sizes would be nice please. Induction is stock still.

EDIT: Looking at Neo's recent post about South Africa... Matter of fact I am in South Africa, but on the coast and I am not planning on riding inland anytime soon. :mrgreen:

vok Evan where did u go that they charged u R2000?
Some doos down here that does custom bikes. R2k was the best price I got at the time. But he never actually did any work...

EvanTate
Settled in member
Reactions:
Posts: 56
Joined: Thu Oct 25, 2012 12:17 pm
Bike owned: VFR400 NC24
Location: Cape Town, South Africa
Re: NC30 carby jetting - DIY guide

Post by EvanTate » Wed Apr 10, 2013 4:21 pm

Quick question about drilling out the hole to 2.5mm. My NC24 sliders have got two holes in them. Can't add a pic right now but there are two holes. Is that standard and should I drill both of them out to 2.5mm?

User avatar
CMSMJ1
Site Supporter
Site Supporter
Reactions:
Posts: 9581
Joined: Thu May 01, 2008 9:42 am
Bike owned: NC30-No9, NC27
Location: Chesterfield, United Kingdom
Re: NC30 carby jetting - DIY guide

Post by CMSMJ1 » Wed Apr 10, 2013 4:56 pm

EvanTate wrote:Quick question about drilling out the hole to 2.5mm. My NC24 sliders have got two holes in them. Can't add a pic right now but there are two holes. Is that standard and should I drill both of them out to 2.5mm?

Don't touch them - they are not the same carbs..

Drilling slides is a hit and miss thing on NC30s anyways.

NC24 are totally different and so leave the slides alone ;)
IMPERATOR REX ANGLORUM

The V4 is the law..

NC30 - No9 > My old mate
2005 ZX10 C1H - smashed it to death @Jerez :(
NC30 - Trackbike...again :)

krisztian_andre
Regular Member
Reactions:
Posts: 555
Joined: Fri Oct 02, 2009 6:49 pm
Bike owned: MG v35 II, NC30, MG NF Mil.
Location: Germany
Re: NC30 carby jetting - DIY guide

Post by krisztian_andre » Mon May 27, 2013 5:41 pm

I'm going on a 300 mile ride tomorrow and I've just rejetted to 112/115 (no time to change it before leaving). The bike is standard except for a full tyga system. Is this jetting safe for the trip if I keep the speed under 80 mph?

Here's a photo of a rear plug after a short ride on the new jets:
http://s7.postimg.org/fethb570r/IMG_20130524_094457.jpg

Another question is, most places only have ethanol blended fuel here, will that further lean out the mixture?

LiteTekBlair
Site Supporter
Site Supporter
Reactions:
Posts: 559
Joined: Tue Aug 16, 2011 3:10 pm
Bike owned: MC22, 3TJ1
Location: Thailand
Contact:
Re: NC30 carby jetting - DIY guide

Post by LiteTekBlair » Sat Jun 01, 2013 2:42 pm

In my humble opinion:
Your plug is showing rich. As I recall, you previously said that your engine only produces 45hp on the dyno. Is that still the case? If true and the reason is lack of cylinder pressure then jetting is basically irrelevant.

Reading mixture on spark plugs is one of the most misunderstood topics of tuning. That said I concur 100% with the first post on this forum http://www.pilotodyssey.com/PO/viewtopic.php?f=9&t=870

Yes, the alcohol causes the mixture to be leaner.

cheers and good luck on the ride
Blair
Carb seal kits in viton & other parts
https://litetek.co

krisztian_andre
Regular Member
Reactions:
Posts: 555
Joined: Fri Oct 02, 2009 6:49 pm
Bike owned: MG v35 II, NC30, MG NF Mil.
Location: Germany
Re: NC30 carby jetting - DIY guide

Post by krisztian_andre » Sat Jun 01, 2013 9:03 pm

LiteTekBlair wrote:In my humble opinion:
Your plug is showing rich. As I recall, you previously said that your engine only produces 45hp on the dyno. Is that still the case? If true and the reason is lack of cylinder pressure then jetting is basically irrelevant.

Reading mixture on spark plugs is one of the most misunderstood topics of tuning. That said I concur 100% with the first post on this forum http://www.pilotodyssey.com/PO/viewtopic.php?f=9&t=870

Yes, the alcohol causes the mixture to be leaner.

cheers and good luck on the ride
Blair
I made it back alright at least. I guess I won't know what's going on until I do a leakdown test and pull the engine apart. It's probably a combination of ruined valve seals and ring problems maybe. I think I hit the end of the road with trying to fix it without a rebuild...

RandomDan
Settled in member
Reactions:
Posts: 150
Joined: Mon Sep 03, 2012 11:41 am
Bike owned: NC30
Location: Cambridge
Re: NC30 carby jetting - DIY guide

Post by RandomDan » Thu Jul 18, 2013 12:07 pm

Iv come to set my pilot jet but when i get to about 1.5 turns the jet becomes loose.
Does this matter? I cant help but think they are just going to jig about once the bike is running!


Post Reply