NC30 carby jetting - DIY guide

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bikemonkey
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Re: NC30 carby jetting - DIY guide

Post by bikemonkey » Thu Jul 18, 2013 12:13 pm

Surely you aren't unscrewing the pilot JET?

You need to set the pilot SCREW.

If it is the screw then something is wrong, might be chock full of seals.

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Re: NC30 carby jetting - DIY guide

Post by RandomDan » Thu Jul 18, 2013 12:17 pm

bikemonkey wrote:Surely you aren't unscrewing the pilot JET?

You need to set the pilot SCREW.

If it is the screw then something is wrong, might be chock full of seals.
Ignore me im being a twat!

Thanks :P

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Re: NC30 carby jetting - DIY guide

Post by NC30Dubz » Thu Jan 16, 2014 12:39 am

This was amazingly helpful, thank you. I have to ask, I've got quite a loud, stubby exhaust can and I'm running jap factory spec main jets. If I was to change these to 4x120 size, is there anything else I need to change? Pilot screws etc.

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Re: NC30 carby jetting - DIY guide

Post by Cammo » Thu Jan 16, 2014 1:06 am

NC30Dubz wrote:This was amazingly helpful, thank you. I have to ask, I've got quite a loud, stubby exhaust can and I'm running jap factory spec main jets. If I was to change these to 4x120 size, is there anything else I need to change? Pilot screws etc.
Generally no, just the main jets to change. The standard pilot screw setting is 2.5 turns out from closed, most NC30's with louder aftermarket mufflers prefer 2.25 turns.

I would recommend using new float bowl o-rings also if you're not sure when they were last replaced. Rick O sells great quality replica o-rings: viewtopic.php?f=64&t=42551

The same goes for carb rubbers - if the bike still has the original carb rubbers then expect a headache getting the carbs back on (if you can at all!). Rick O can supply new carb rubbers, also available from David Silver Spares or Honda dealers etc.

Glad it helped.
"It's just a ride" Bill Hicks

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Re: NC30 carby jetting - DIY guide

Post by NC30Dubz » Thu Jan 16, 2014 4:07 pm

thanks, the pilot screws are currently set to 2.25, feels a bit boggy so thought id have a look at different jets. just emailed rick, hopefully have some new parts soon!

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Re: NC30 carby jetting - DIY guide

Post by NC30Dubz » Tue Jan 21, 2014 3:50 pm

Ok so I got a set of 4x 120 main jets and a set of washers for the carb needles. Installed everything and now it won't happily rev over 10k. Very boggy. Could it be that the bigger size main jets (they were 110's) are overfueling the carbs? Thanks.

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Re: NC30 carby jetting - DIY guide

Post by vfrman » Tue Jan 21, 2014 7:24 pm

That's a good place to start. This symptom is on the road, right?

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Re: NC30 carby jetting - DIY guide

Post by NC30Dubz » Tue Jan 21, 2014 8:46 pm

Ok. It could be fuel starvation aswell thinking about it, but I wouldn't understand why? Yes, it was on the road, took it for a run after fitting the jets and washers, was fine on a low speed run but as soon as I went full twist, the bike didn't like it

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Re: NC30 carby jetting - DIY guide

Post by bikemonkey » Tue Jan 21, 2014 10:27 pm

I'd say that you need 118's.

I run 118f 120r with a half system, not just an end can, and it works great.

Have you got any washers under the carb needles?

Also is your intake standard?

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Re: NC30 carby jetting - DIY guide

Post by NC30Dubz » Tue Jan 21, 2014 10:33 pm

I've got a yamamoto half system with a stubby exhaust, yes its a standard intake minus a bit of the plastic, there is 1 washer as standard on all the needles, added an extra 0.5mm washer to each at the same time as the jets.


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