Hi
Don't know whether anyone can help but my NC29 trackbike is struggling to pull around 10 and 12000 revs in the top 4 gears. 1st and 2nd gear pull through the revs fine. It has never been a problem before in the 3 years i've owned the bike.I've changed the spark plugs but that hasn't solved the problem.It's very annoying as it feels as though it is only running on 3 cylinders but as i've said before it's fine in 1st and 2nd gear.
Any help would be much appreciated
Cheers

The entire race field at Phillip island had this problem in 5th and 6th last year, where the morning temp was so cool, everyones bike was running too lean. Hardly anyone could pull through to the redline, until the arvo when it warmed up and the air thinned out a bit.

Check your plugs and see if they indicate leanness (dry tan appearance) or richness (black, blacker and dirtier than the inside of a cats bum),
Check your fuel filter and fuel tap are flowing if you are confident the carb settings are correct.
Have you changed to a funky alloy fuel cap? Make sure it has a breathing hole drilled in it or your tank will vacuum and your pump might struggle to suck fuel out. (so i'm told)
Check that the carb breather is unobstructed too, I pinched mine and it stopped the float bowls from filling.

If you aren't confident your carb settings are good, then use the plugs as an indicator and do some tuning, or take it to a dyno man hand him some cash and say 'fix please'

Wait, 3 years? What maintenance has been done? What happens on a constant throttle? Does it rev fine at a stand still? When was the last time you checked compression etc? A 3 year old motor probably has more than just fuelling issues...

Hi greggo, vis a vis your last ..... the possibility of fuel tank vacuuming on my NC29 may explain an ongoing problem that I am trying to track down. The filler cap is standard, but I'm not sure what the breathing arrangement is. Can you describe, please? Cheers.

sometimes if the battery isnt in the best condition,it plays up with the electrics...fluffs with the cdi apparently,causing a miss,andn struggling in the higher gears...just another thing to check anyways
stimpy

lack of power = poor pulling power in higher gears
The usual checks - healthy sparks, correct air / fuel ratio & compression

Thanks everyone for your help

I got your email the other day mate, Sorry didnt reply so quickly, been busy.

The problem with my NC29 turned out to be poor contacts in the side stand switch.