Constant misfire on NC30

[emto]

After giving the carbs a major overhaul, including raising the needles, balancing, setting the A/F screws to 2.25 & replacing the plugs etc., I'e got this annoying misfire which I originally put down to running a bit rich with the extra shims on the needles. However, it's all the way through the rev range and gets more pronounced the higher you go,(obviously).
Where should I look? Electrics, HT's, coils, fueling or something else?
It's booked for a dyno run next week & at this rate it would be a waste of money.
Any help most appreciated.

[viper_biker]

Could well be an air-leak. Cheak that the carbs are fitted securely.

[emto]

Thanks Viper, I did fit new carb rubbers as well and I had a terrible time trying to refit the carbs.
I'm fairly sure they're ok but I'll check where the rubbers attach to the engine, one seemed to go on too easily??

[MexicanGringo]

After cleaning why did you raise the needle heights? Was it running overly lean at any rev range? What was the colour of the plugs before?

Having it dynoed might actually help to get it running ok, and then maybe optimised if it doesnt take too long initially..

Heres a relatively optimised setup, tho 14.7 is more what your aiming for throughout the range(thanks to Chris Gunster)


Raising needles might have taken it just too much out of an acceptable range..
Also is your air filter clean? A freer flowing filter might lean out your raised needle mixture.

If it was firing alright before the cleanout & adjustent then electrics shouldnt be the prob

Colin

[emto]

Thanks Mex,
It wasn't firing perfectly before, but only on idle. I raised the needles to improve the mid range, but there was no flat spot.( plugs nice tan colour) but it certainly made a difference in pulling power. The air filter is new. I think I'll remove the needle shims and see where I am from there. The air leak is also a pos. Optimum of 14.7 sounds high for fuelling? I'm still thinking electrical, dodgy HT or something.
Thanks for your help, any further input appreciated.

[MexicanGringo]

Any progress mate? Have you checked the electrics over and possibly tried a different cdi, coil, coil lead, regulator/rec?