Advice on carburettors nc35

[LennonRVF400]

I have an aftermarket system on the bike that I'm told could be causing my flat spot at 5000 to 6000rpm. Im planning on getting the carbs ultrasonicaly cleaned, is their any simle upgrades for the carbs to get rid of the flat spot.

Cheers in advance

[CMSMJ1]

Get on a dyno and see why there is a flat spot...and go from there. It is really the most effective way of finding out what is going on.

[LennonRVF400]

Thanks for advice

[Neosophist]

flat spot is also common in this range as it changes from needle jet to mains..

on the nc30 at least raising the neeldes with a shim richens it up and fixes that issue.

the advice abouve is the best, get it on the dyno and see what the mixture is doing around there and go from there :D

post your current carb setup too and youll have plenty of people on here advice you on what is best

[LennonRVF400]

Carbs are standard nc35. .. The flat spot doesn't seem to be their when the bike isn't fully warm .. This is my first road bike so I'm lacking in nollege a bit... All advice is welcome thanks

[CMSMJ1]

Where in the world are you? Not anywhere high up or extreme temps?

It getting worse when warm would seem to show that it is something easily sorted - a jet change, a needle washer or a tweak of the air/fuel jet. Dyno run will show you where to start :)

[LennonRVF400]

I'm in Ireland... Thanks for the advice

[racingt]

Mine was running stock jets and needles with horrendous flat spot, on standard system with different end can.
I went up to a larger jet size,(I think 112) , small shim under the needles, checked the float heights, bike idels perfectly, runs sweetly throu Rev range now. Cost very little, took an afternoon.
Of course, dyno time would be good, but that may be 2 or 3 visits, plus cost of bits. Depends how much time and cash you have and how much of a good result you want. I'm pretty happy with mine, maybe I could be happier, but I'm guessing not a lot. Not saying anyone else is wrong, just there are different points of view on this one.

[richyrd5]

Yes.i would whip carbs of.set floats and clean all jets.etc..check air screws and depending on jet sizes go for 1mm shim under needles.should run A LOT better and will probably cancel flat spot.but i understand why the race boys say get it on a dyno!!.

[micpec]

Always make notes of the starting condition/point of the carbs and go from there. Would advice to patienly make adjustment in little steps only and not overrush with bigger jet sizes, or thicker shims other than the next increased size (0.5mm for shims) or even different aftermarket needles with adjustable height. It will get you easily way off the wished path.