5 days to go before sva and the engine has developed a misfire on number 2 cylinder. This is what i have done since last running the car.
Drilled out main jets to150 (stupid or what) which caused the engine to run way to rich. I then aquired a set of dynojet 120 main jets and fitted them seems to be a bit better but still misfiring. The plugs where all black with soot but now 1,3,4 are ok and 2 is still black and a wee bit wet. I have checked carb 2 and all seems ok. The original jets are stamped 112.5. Looking for any pointers or help to resolve soon.
Thanks

Sounds electrical to me maybe plug or lead or even coil, if fuel all four would suffer

What engine / size 1.8 /2.0
and what carbs zx9r /r1 give us a clue

i've been told that once a plug gets wet its useless. Not sure how true it is, but i've also heard that to 'recover' a plug put it in the flame of a (thing, burns butane, torchy err, can't remember the name)

it 'dries' it out. Might be worth a go.

Do dyno jet size there jets in the same manner as OEM? I know that on bike carbs (thundercat) dyno jet sizes were completely different from std sizes. Can't remember if they were bigger or smaller for same jet number.

Is everything else ok on no.2 ?

1: try swapping plugs and leads to another cylinder and see if problem moves or stays

2: Valve clearances ok, not tight on no.2?

3: Try std jets back in

Just a few thoughts which sprang to mind.

Davie

Check the outside porcelaim of the plug for flash over if you find sign of flash over or carbonising of the rubber Fit a new plug and plug lead

Also reduce all the plug gaps to 1.0 mm (0.40" rather than 1.3 mm.

Have you swapped the plugs over from one cylinder to another to try and see if that one specific plug is a problem?

Steve

I am running a zetec 1600 with mjlj and daytona 1200 carbs, everything seemed to be running fine before i resized the mains. Dyno jets flow better than oem ones.

Problem solved it was a sticky flaot valve.