Hi All,

I had my NC30 on the track for the first time since I got it and I had some issues with it bogging / missing / not accelerating in certain spots. Below is whats happening, when and what carb setup I have, as I am not sure if it is fueling or spark.

What is happening and when:

When accelerating, or hard accelerating with the reves between (approx) 7-9K RPM there is no drive, you can hear the engine missing.

What I observed:

It appeared to happen when there were bumps, and from the apex of corners when getting hard on the gas or where it was bumpy and was at full throttle.
I tried adding fuel to the tank to see it it was starving at lean angle, this did not help.
I then thuought it may be a spark issue, maybe a loom or HT lead issue I checked connections of coils etc, all seamed ok, but this was just pull apart blow and put back on.

I then tried to ride the thing above 9K RPM even at the apex of corners and this seemed to work so I now think that it is probably fuelling in the "Mid range" that I have read a bit about on here. It appeared to be worse if you went from trail throttle to WOT quickly but was not present if you kept the revs above 9K.

It seems fine at WOT and above 11,000rpm. Also the bike revs to 15K, not sure what this means or if it matters but I can only see one CDI box on the loom and there is also no key or speedo.

My carb set up:

Std needles, drilled slides 2.5mm, standard springs (I think), standard 1mm washer under needles, 120/122.5 Main Jets, std pilot jets, std emulsion tubes, float height 6.8mm, air bleed screw set to 2.25 turns out. Rubber flap in, standard airbox and snorkel with area removed beneath the snorkel, standard air filter that is not new but not totally rooted.

If it is too rich in the mid range, which I think it is because when I rode it like i hated it it behaved, how can I fix this?

Should I:
- modify standard air filter and repalce paper element with air filter foam thus making it leaner everywhere
- change emulsion tubes or something else as it appears to be in the transition from pilot to main jets.
- Reduce main Jet size
- dick around with slide springs
- OR, Anything else you can suggets.

Your help is appreciated.

You could try undrilled slides and a standard 0.5mm needle washer, Not all NC's like the extra fuel in the midrange.

What do you mean by the area below the snorkle is removed? surely thats the rubber flap and that should be there really.

999Gomerz wrote: standard airbox and snorkel with area removed beneath the snorkel

Which part is removed?

Any airbox changes have can massive effects on the performance like you're seeing.

Thanks Guys,

I made an error, there is the standard shim under the needle which is 0.5mm.

The part that has been removed is from the airbox base, the bit that extends forward to seal in the triangle section of the frame from the air that comes in from the rubber flap has been removed. Allowing air that is channelled in from the rubber flap to be sucked in through the snorkel.

I will try first removing the air filter and see if this makes a difference, then I will try putting my other standard air box base in and advise the results.

Thanks for your help.

Cheers,

999Gomerz wrote:Thanks Guys,

I made an error, there is the standard shim under the needle which is 0.5mm.

The part that has been removed is from the airbox base, the bit that extends forward to seal in the triangle section of the frame from the air that comes in from the rubber flap has been removed. Allowing air that is channelled in from the rubber flap to be sucked in through the snorkel.

I will try first removing the air filter and see if this makes a difference, then I will try putting my other standard air box base in and advise the results.

Thanks for your help.

Cheers,

The bike likes t have this in place.. get one and fit it, you'll see it improves.