Running very rough below 4k

[trademe900]

hey guys sorry for all the threads recently but i've got issue after issue (different bikes).

Basically just got this nc30...this one pulls really hard above 7k!

4-5k is nothing special but that should be fairly normal with running an aftermarket exhaust with better mid range.

The problem is under 4k, at about 3.5k and under actually. Basically when you slip the clutch and pull out or whatever it just sounds like what can only be described as mush or spluttering and has little power. As soon as you get over 3.5k it's totally normal and picks up suddenly. Strange thing is that it idles pretty well. Starts up easily. Also in neutral revving it, revs through this range no problems. Only under load.

I don't really mind since you'd never ride the bike at those revs but with the really tall first gear it makes pulling out a little hard on the clutch when constantly having to rev it over the rough spot.

Bike is running a pretty loud exhaust, stock filter and airbox with snorkel.

Any ideas on this one?

[MexicanGringo]

Does it hesitate on slow acceleration as well as hard acceleration?

Pilot system may be running rich if its starting very easily, does it get worse / better when bike is warm?

What size pilot jets?

How many turns out are the pilot screws?

How dark are the plugs after a period of low speed / low rev riding?

At least one of these is bound to indicate the problem

[trademe900]

hey man, all i know is that it runs better at that spot when warmed up for sure.

at low rpm it hesitates on slow and hard acceleration.

Not sure about pilot settings yet.

[MexicanGringo]

My bikes actually got the same problem at the moment, prob not as bad as yours but its def a hesitation around 3 - 4k, i've still to try some bigger needles from cammo to improve an overall richness, but running a freer exhaust brought about this hesitation so im thinking lean at 3-4k. Try adding a 0.5 washer to each needle, and also try decreasing the float heights, for more fuel at low rpm.

If its running very rich at moment, your plugs will be dark black, then increase float heights & see what happens.

Get yourself a haynes workshop manual if unsure how to adjust these, you'l use it for the whole bike eventually...