Needle and jet help

[Bike_Nut]

Hi

I am busy trying to improve my NC30 and when I stripped my carbs it looks like someone has already fitted other needles and jets. The needle has J6 stamped on the shaft and was wondering if that means anything to anyone? Or should I just get the jet kit from NC30 club and start from fresh?

Also, it has 117 fronts/115 rears. Isnt this the wrong way round? Mind you the manual has a uk spec bike as being 122F/120R so any help appreciated. The jets also are unusual - they have a hex to fasten not the usual scewdriver slot, and have 3 holes drilled at an angle leading to the single jet hole.

Thanks

[CMSMJ1]

the jets sound like bakudan jets - 3 little holes is spot on.

no idea bout the needles - stick us a pic in if you can.

Welcome to the site

[Neosophist]

There non-standard jets, sound like bakudan jets with the holes

The rear cylinders usually run a little richer (bigger jets) but you may find you have more holes in the emulsion tubes (jet holders)

Is it running badly? If it has aftermarket jets in im presuming its already been tuned by somone.

Have you checked out Rick Olivers parts list?

[fastdruid]

The matching bakudan needles look like this



Druid

[Cammo]

The nc30 bakudan needles are stamped J51a/b same as standard needles.

[Bike_Nut]

Spot on guys, you know your bikes well. On stripping the other 3 carbs the J51a/b marking seems correct and the needle looks just like the one in the picture (cant figure out how to post pics). Are these needles similar to standard?

I have looked at Rick Olivers stuff but that all seems to be full race parts, mine just has a better exhaust can and HRC electronic box so following an article written by him suggesting a mod to get more fresh air to the carb by modifying the scoop arrangement, drilling the damping holes to 2.5mm and then jetting the bike to suit. Just need to figure out if I should maybe rather fit say 117F/119R

The bike was running well before I stripped it so I can always go back to base setting if I get it wrong.

[Cammo]

That all sounds ok but I'd be inclined to leave the airbox/scoop exactly as standard. Minor changes can make big problems, it it's running sweet best to leave it.

The larger jets should certainly be in the rear carbs though (J51a needles rear, J51b front). Easy to check the pilot screws while you have the carbs off also (set them to 2.25 turns out).

[Bike_Nut]

I swapped the jets around last night, but I did not know the needles order so I will strip the needles out again and see that they are correctly inserted - could be tricky as the markings are almost gone on some of them.

As for the airbox mods, I know that a friend of mine did the mod and the bike would not run nicely at all - far to lean so he sealed it up again. Still, if it goes lean it means its getting more air which is what I want. I kept the holes a moderate size and made it as far from the snorkel as I could to limit the ram air effect, rather just wanting a supply of fresh cool air. I have spoken to TTS about some dyno time so they should be able to fix any jetting issues.

Do you know if the bakudan jets are available in the UK? I do think they will flow slightly better than standard as my bike was definately not running lean on 115/117's but I imagine I will need to go larger now.

Next search - problems with airbox mods lol

[superlite]

The Bakudan jets pop up every now and then from Japan, but aren't readily available. I wouldn't keep using them. They're not proven as regular jets are, and no one really knows how their jet sizes correlate with regular style jets (you could find out for us though!). They're not bad, just different and unknown.

Be careful with the airbox mods - the little NC30 is a strange beast when it comes to fuelling

[Neosophist]

Next search - problems with airbox mods lol

Loads!! Good luck with that, might be worth getting a spare airbox so when you have it dynod you can swap em over at some point, see the differences between em.