NC30 surging in the states

[purcellj]

So I'm one of the lucky few with a 92 NC30 titled for the street in the US.

Currently when running around 6k rpm with a steady throttle I've noticed a minor surging. I believe it's dirty carbs from lack of use. I throw myself at your feet for forgiveness for this lack of use sin.

First, do you concur that this surging is dirty carbs?
Second, is anyone aware of equivalent USA-spec bikes that use the same carbs, like a CBR 6?
Third, if a USA-spec bike not known, where can I get a carb maintenance kit (gaskets) from?

I have to mention one of the joys in life is watching bikers walk by my 400 and see the double and triple looks. They simply can't wrap their heads around a V4 400.

Thanks
John

[Cammo]

Nice ride! Mine have always surged a little at those revs. You can improve the fuelling by installing an extra 0.5mm washer under the carb needles (they have 1 x 0.5mm standard), they run very lean at 6k rpm (probably to get around noise/emission regs). The extra washer makes it a little richer at mid revs and can help with the usual flat spot there.

I'm afraid you're out of luck regarding other models that use these carbs, even the rvf400 carbs are different.

[purcellj]

Thanks for the reply. I don't remember the surge-ness being as noticeable.

[Neosophist]

Try backing your pilot screws out half a turn before you take the carbs apart... 6k rpm and on very little throttle (crusing) the bike will probably be running very lean as Stickshift has said.

Richening the pilot up a bit sometimes helps a lot..

[Sligeach]

in terms of your carbs from any other bikes, you are out of luck.

the cbr 6 is an inline 4 with all the cabs in a line, as in X X X X

the VFR400 is a V4 so the cabs are orgaised two lines X X
X X


you can probably get a gasket kit off some of the members on here, just not sure which ones

[purcellj]

Neosophist: Thanks I'll try the pilot screw adjustment

SligeA¡ch: Yes I'm aware of the engine block and carb configuration between the CBRs and VFRs. That doesn't preclude the same gasket kits being used -- if the carbs are similar. Carb Linkage is a completely different matter.

I've maintained a VFR400 cross-reference to USA spec bikes for years ...
http://www.john-purcell.com/motorcycle/ ... erence.htm
You'll note several references to CBRs already.

[CMSMJ1]

Hi John,

I have mailed you a fiche mate. It should help you track a few bits and bobs down/

I'll have a look to see if there are matches in the CBR fiches I have for gasket sets.

I would probably email Graeme France or Rick Oliver on here - They'll likely post international and are well respected guys.


Float chamber gasket set is 16010-MR8-003 for an NC30 and 16010-MV4-000 for an NC29

Nothing similar as the chamber in the 30 has to avoid the linkages...

[purcellj]

Very much appreciated!