NC23 Cbr400 Misfire

[Html33]

Hello all just recently i have developed a slight intermittent fault. In the last two weeks (started when the weather was dry) i have been having an intermittent misfire, but more so when under load.

Normally in the mornings the bike seems fine, i can ride for miles without a problem using 1/4's throttle, 2/5s throttle through the gears fine no problem, and get to 70mph+ and maintain that speed firing on all four, but as soon as i throttle hard, i get a stuttering and misfiring, and i can clearly hear and feel it's not running right, come back of the throttle a little bit (back to 1/4) and the bike slows down obviously but feels better, but there can be moments when the bike is pulling hard for 30 seconds and then will start crapping out.

This too me made me think it was a carb issue or spark, like one of the main jets..

I normally flick my lights on as soon as i pull off, essentially always having them on, except from when starting.

But today, I noticed that when the lights were off, the bike ran flawlessly under hard throttle (still need to test this on a longer ride as i only discovered it earlier), and whilst accelerating hard i switched the lights on and the grumbling, poor revving misfiring came back, flicked the lights off and suddenly the bike started pulling hard.

I've done this several times now and it's not coincidence, it definitely seems related.

Just wondering what the cause of this could be? If you had any previous experiences with any similar scenarios?

Gave the bike a service a month and a half ago, and was running the same after so weren't that..

I have checked all the HT leads, the screws in the cap are tight and made sure the lead is pushed firmly into the cap.

Rectifier cooked my battery last winter when that went faulty, was replaced with a good known second hand one (at the time...) is this a possible cause? There has been two or three occasions when i have started the bike at 10pm after sitting for several hours, turn the lights on and the bike seems a little boggier and stalled a couple times.

Again, i need to check this but i'm pretty sure the fault was both evident on the first and second click of the lights, but as soon as they were turned of a bolt of power came back.

Now i think about it, not sure if it could be related. But my dash lights (also connected into the same feed on the light switches?) have been flickering in brightness, and randomly going off (not often) i looked down the other day and noticed the rev counter light was off, look down moments later and it was back on however the temp gauge light remained on the whole time?

Could it be a ignition coils breaking down under load or requiring more power because of a higher resistance (worn out?) and then when the lights are turned on theirs not enough power provided by the stator coil, and then under load is causing a mis-spark/misfire?

Many thanks, sorry about the long thread

[sketchy]

I think that the HT lead plug cap has a resisor in it that can breakdown. Check the resiatance of your HT leads as a whole. There is a spec of what this should be. I cant remeber where i have sean it, mabey in haynes. but hopfully somone else will confirm this