hi, ive been on this site b4 for some help,i bought a 92 nc30 wich was stood for a couple of years when i got it home i cleaned everything carbs too,she started first time and idled tidy but failed 2 rev cleanly i checked 2 connection behind speedo all plugged in and no broken wires, even the disc inside the speedo had been removed,had the carbs set up new jets and float height checked and new gasgets, she wil start first time on the choke warlm her up and let her idle about 1 1/2,and she sweet she wil rev ok to 5k,but after that she struggles til about 10k then she kinda clears out, i havnt botherd with it since last time as it was doin me head in,so i thought id have another go at it,thier is no t&t on it so i cant get her up the rd 2 ride her,and dont fancy getting caught or brakeing down lol. this is was bought as a poject, as i use an r1 for commuting around. id be really greatfull with a little help

it might be worth trying another CDI/ECU you apear to have done the right checks that normally come up after the 5k rev limit issue,

have a work with member geoff33

Checked plugs? Leads? Coil packs? I'd say one or two plugs are fouled up and not sparking properly, if it's laggy in lower revs.

Done electrical tests? Battery / Reg/Rec?

Might not be producing enough power at low revs?

Stock standard airbox and filter?? Modifying these parts can cause similar symptoms.

fit the 2k2 resistor to the speedo plug (outside two wires), just done it to mine and she's revving clean as a whistle now.
read on here somewhere that if theres a fault in this circuit it can cause this problem, tried it and seems to work.
if it doesnt its only gonna cost you a few pence for peace of mind but it could save you heaps more work.

Agree with mossey, had similar problem to yours and I fixed it by changing the sensor unit in the speedo. Had a spare speedo and did not know about the resistor trick. Faulty sensor looks like no sensor to the cdi unit.

The fact that it revs clearly after 10k doesn't suggest a speedo circuit issue. It's easy and cheap to test so go ahead and do it.

10k+ would be main jets... the hole in the middle would be your needles and mains.

You've been messing with the carbs i've re-read.

Did you put the right Jets / needles and emulsion tubes into the right carbs? All the parts are different and should not be mixed up.

What are the float heigts set too?

Are the pilot jets set to the right number of turns and spring / washer / gromet all present?

Mine did exacly that, had it taken in and they put carb in ultrasonic bath to clean, rejetted and sync the carbs. now she runs smoooooooooth>

checked ht laeads all fine new plugs new battery new reg/rec so cant b them,the carbs are standerd for this bike i do have a spare set of carbs that i had of a mates bike and that was running tidy, they were standerd and she does the same with them on 2. the bike has not been up the rd for a couple of years would that have anything 2 do with it?