NC30 carby jetting - DIY guide

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Jono035
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Bike owned: '90 NC30
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Re: NC30 carby jetting - DIY guide

Post by Jono035 » Wed Apr 01, 2015 9:39 pm

Good stuff. Did this a few years ago (didn't drill the slides, though) and got the bike running beautifully. Had the carb balanced by a local mechanic who specialises in VFRs and that made a big difference to the throttle response. The other thing was swapping the CDI out for the Ignitech unit with the standard improved map. No more mid range flat spot at all, just clean, building torque all the way up. Highly recommended!

Icemaestro
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Re: NC30 carby jetting - DIY guide

Post by Icemaestro » Thu Apr 02, 2015 6:31 am

Oh yeah? Did you get the cdi from rick o, or where otherwise? Running standard exhaust/jets or what? Do you still have your bike? The silver one?

Jono035
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Re: NC30 carby jetting - DIY guide

Post by Jono035 » Thu Apr 02, 2015 7:00 am

Oh, hey man! Yeah, still got the Silver one. Haven't ridden it much this summer with all the other things cropping up, but hoping to get at least a few more outings in before it gets too wet.

Yeah, CDI was from Rick O. Easily the best money that I've spent on the bike, so far. I'm running Dynojet mains from him as well, 118s front, 120s rear. Standard exhaust but aftermarket stainless Zorsts muffler.

Edit: Just found the original invoice, RO Road needles, as well.

Icemaestro
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Re: NC30 carby jetting - DIY guide

Post by Icemaestro » Thu Apr 02, 2015 9:12 am

Gotcha. I reckon it would be the needles that sorted it. I've got them too as well as same 118, 120's

Jono035
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Re: NC30 carby jetting - DIY guide

Post by Jono035 » Thu Apr 02, 2015 9:25 am

I did the two separately. Cleaning up the carbs and replacing the jets/needles made a decent difference, but the flat spot was still there. The Ignitech made it disappear completely. I haven't tried changing the advance beyond the standard map or trying to use the higher octane map to see if that makes more of a difference, it was the around-town ridability that I was looking for.

burtonbiker
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Re: NC30 carby jetting - DIY guide

Post by burtonbiker » Sun May 07, 2017 12:24 pm

Thanks for this Cammo - I would never have tried to clean the carbs myself without your guide. :grin:
I am leaving the settings alone as it has previously been done on the dyno and ran OK until getting bunged up. I am going to order new pilot jets, but was wondering if I replaced the emulsion tubes as well (which don't look too bad, just not perfect in the middle of the tube, but not worn oval or anything) might this affect the settings much - ie because the old ones are presumably a bit worn and would have been when it was set up?? Or would that be a bit over the top? My other question is there any need for me to remove the slides? - thinking on the lines that if I leave well alone I reduce the possibility of messing something up when putting them back! NC35 btw not 30, mains and emulsion tubes a bit different, not sure how much needle has been lifted... Cheers!

maxhemacrit
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Re: NC30 carby jetting - DIY guide

Post by maxhemacrit » Thu Jan 11, 2018 12:12 am

Hi All,
First post.
I have just purchased a Japanese NC24, I live in Vancouver, Canada
I searched but could not find the recommended Main Jet size.
I understand these bikes (Japanese) are typically set up lean?

RizomaKat
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Re: NC30 carby jetting - DIY guide

Post by RizomaKat » Thu Jan 11, 2018 11:36 am

maxhemacrit wrote:
Thu Jan 11, 2018 12:12 am
Hi All,
First post.
I have just purchased a Japanese NC24, I live in Vancouver, Canada
I searched but could not find the recommended Main Jet size.
I understand these bikes (Japanese) are typically set up lean?
I hope this helps. Main jet sizes front are different size to rear ones on earlier models

NC24 Carburation
Main Jet size #115 x 2 rear carbs, #112 front carbs (later models, 4x#115 as rear cylinders have bigger emulsion tubes with an extra hole) fits inside ...
Emulsion Tube/ Needle (main) jet holder: rear carbs 16165MR8780, front carbs 16165ML0721 (discontinued)
Pilot/slow jet 4x size #35
Float seat, filter and float valve: valve seat set 16046MG9681
Float height is 6.8mm
Pilot screw set 16046MG9681
Pilot Screw Setting 2.5 turns out
Drain screw 16016ML7004
Gaskets: 4 float bowls, 4 velocity stack air inlets, 4 fuel hose connectors, 4 pilot screws,
Idle Speed Knob setting: 1300rpm +/-100rpm

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TZcRank
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Re: NC30 carby jetting - DIY guide

Post by TZcRank » Tue Jan 22, 2019 10:09 pm

Excellent info here! Just one question. I live at approximately 1700 meters above sea level.

Obviously the jetting at this altitude will be a bit different from what seems to work for you guys which I will figure out later but my question is will the drilled slides and needle spacer have the same effect with less atmospheric pressure and slightly reduced oxygen in the air?


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