Emulsion tubes & jet positions in UK NC30

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Sunnyday
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Emulsion tubes & jet positions in UK NC30

Post by Sunnyday » Thu Jun 11, 2020 10:01 am

Hi all,

Hope you are safe & well, can any expert advise me on the following direction I should take I have a UK NC30 that is fitted with:

122 at the front with 4+1 hole emulsion tubes
120 at the rear with 4 hole emulsion tubes

My questions to the experts are would you change this current placement of the emulsion tubes and would you run a bigger jet in the rear has anybody got any experience on this. My issue after a layup the carbs have been cleaned and blew out with an air line and are confident they function as they should but its lost its urgency to pull as hard as it used to its flat from say 9 onwards it will eventually get to redline in lower gears. The bike has always been reluctant to pick up from idle you could kill it easily if you are to quick when twisting to quick however when running on the road it has been totally faultless.

I have just brought the valve clearance within tolerance, fresh fuel, balanced the carbs to perfect, it starts and ticks perfect picks up quick from idle in neutral the bike does respond to throttle openings but its lost its pull and I hesitant from 9 k with coming and going of power. in the lower gears I can get it to redline.

I have some new slightly bigger main jets on the way that will give me two size options to try and also some new needled to try from Rick regarding the current placement of the emulsions tubes and bigger jets to the front he has suggested I ask the wider forum for thoughts and views & hopefully experience on what will work the best, as you can imagine I want to set it up the best way I can the bike is standard in every way apart from a viper can that has been shortened slightly by about 40 mm.

The float heights are all now set to 6.8 mm ready, I took the two rear spark plus out to find one was a light tan colour which I believe is right and the other was very very pale with next to now colour on it.

Fire away guys, I am not a mechanic but I can manage with this job ok so be gentle with me...…………….

Thanks in advance
Last edited by Sunnyday on Thu Jun 11, 2020 7:25 pm, edited 2 times in total.

Sunnyday
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Re: Emulsion tubes & jet positions in UK NC30

Post by Sunnyday » Thu Jun 11, 2020 6:58 pm

update:

Ok So this afternoon I have fitted new needles with the washers that was used as standard fitted new 125's to the front & 128's to the rear along with swopping the 5 hole emulsions to the rear it's started great and seems to pick up fantastic static in the garage when up to temperature. I guess the acid test is how it pulls under load with me on it and what colour the plugs are.

Regards to all.

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CMSMJ1
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Re: Emulsion tubes & jet positions in UK NC30

Post by CMSMJ1 » Thu Jun 11, 2020 10:09 pm

Now then :)

So - what's your airbox setup - absolutely standard? nothing missing, or pieces cut out from the airbox etc?

in the UK and standard - The general consensus would have been that you are going to be really rich with those jets. The bikes are bloody fickle with regards to induction so removing a flap 'to get more air in' has been the cause of issues before. The bike needs a still volume to suck it;s air in - there is no benefit in copping airboxes up unless you are then going to go fully open/HRC carbs and fuel pumps etc

Standard is usually, once all is clean and sorted, bang on the money
IMPERATOR REX ANGLORUM

The V4 is the law..

NC30 - No9 > Being rebuilt
NC30 - In lots of pieces

Sunnyday
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Re: Emulsion tubes & jet positions in UK NC30

Post by Sunnyday » Fri Jun 12, 2020 8:58 am

Hi,

The bike is totally standard apart from a shortened viper can. Why as standard in a UK bike would the smaller jets be located in the rears with smaller 4 hole emulsions and the bigger jets and more holes in the emulsion tubes fitted to the front when the general rule seems to be run larger jets in the rears they are all the same engine apart from an oil cooler?

NB I also fitted new needles from RO that were a fatter profile than the standard ones so that will have a lean out effect.

When I get the chance I am going to see how it runs & pulls, smells and check the colours of the plugs.

Cheers for you input.

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Re: Emulsion tubes & jet positions in UK NC30

Post by richyrd5 » Fri Jun 12, 2020 2:59 pm

Standard UK spec is 122 rear with 5 hole emulsion tube..120 front with 4 hole emulsion tube..so that was wrong in first place....the Rick o kit is primarily to pull the midrange flatspot out with the shim...I'd go back to standard jets/tubes...just a viper can won't need a major upjet anyways..let us know how you get on bud

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Re: Emulsion tubes & jet positions in UK NC30

Post by Sunnyday » Fri Jun 12, 2020 4:39 pm

Hi Richy,

Ahh ok,

That's very good to know I suppose its worth a try in the correct standard way with the standard jets but with the RO needles I am now a dab hand at getting the carbs on and off once over I though it was a nightmare its simply not if your patient.

I had a small run out between rain showers this afternoon with the 125 plus 4 holes front and 128 plus 5 holes in the rear and it did feel like it pulled stronger but didn't have the full opportunity to stretch its legs however I believe it still had the renowned flatter spot maybe not as bad before it started to pull I need to get it hot and push on a bit at through all gears to evaluate I thinks, I have fitted the new needles with the washer that was already there not sure if I should have done...and do you know I didn't check the needles Rick supplied I thought that they would all be the same length maybe I need to drop him a line I just pulled them from the card and went ahead and fitted them.

I suppose now I have a few options to try out so to confirm you should you ALWAYS run slightly bigger jets in the rears along with the 5 hole emulsions ?

Thanks again for your time & interest mate.

Appreciated.

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Re: Emulsion tubes & jet positions in UK NC30

Post by Sunnyday » Sat Jun 13, 2020 8:15 pm

Update guys,

I ran the 125 in fronts 4 hole emu's + 128 in rears 5 hole emu's to find it had a flat / hesitation spot in a high gear at around 5-6 k so took it straight back to the garage and this is what I did.

Pulled carbs back off took each diaphragm out again cleaned & lubed with silicon spray then actually polished the new needles lightly I will add to a high shine and reinstalled, removed the jets and then polished the inside of the emulsion tubes with garden twine would you believe and some autosol again very lightly I then twisted some electrical fine wire and fed it through each hole in the emu's with carb cleaner blew out with an air line and reinstalled as standard or as it should have been this time... with the 120's to the front 4 hole & 122's to the rears 5 hole and put it back together.

The result is a bike that now pulls hard with no hesitation and pulls harder the closer you get to the redline, I was that confident that after 25 mins or so of pushing on when it was hot to see what it will do I returned with a smile on my face to the garage and rebuilt the bike again fully as a finished article.

Maybe there was a rogue unseated diaphragm or the new jets were too big I don't know as the emu's where cleaned prior to last set up but this time I took them to another level and fitted the standard jets but in the right place and with the emu's in correct place.

For this season the bike has had all the recently fitted brakes pads removed cleaned, pistons cleaned & new fluids, new rear braded line, new coolant, oil changed ( it had only done 1500 since last change so left the filter this time, new chain and sprockets so its all ready.

In summary I am very happy with the bike now it's all ready for a Sunnyday...

Thanks and stay safe.

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Re: Emulsion tubes & jet positions in UK NC30

Post by CMSMJ1 » Mon Jun 15, 2020 9:52 am

That is good news :)

My bike is off being sorted at the minute - looking forwards to riding it!
IMPERATOR REX ANGLORUM

The V4 is the law..

NC30 - No9 > Being rebuilt
NC30 - In lots of pieces

Sunnyday
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Re: Emulsion tubes & jet positions in UK NC30

Post by Sunnyday » Mon Jun 15, 2020 7:01 pm

Been out today for a shortish run and the bike pulls hard all the way to the redline in every gear I dare not tell you what the speedo was telling me, its a different bike its relentless picking up when pinned it sounds angry.

I am over the moon with it.

Stay safe everyone.

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Re: Emulsion tubes & jet positions in UK NC30

Post by CMSMJ1 » Mon Jun 15, 2020 10:46 pm

#winning
IMPERATOR REX ANGLORUM

The V4 is the law..

NC30 - No9 > Being rebuilt
NC30 - In lots of pieces


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