C20NE Misfire Checks

[paul91085]

My C20NE has developed a bad misfire and i want to know what things i should be checking? It started off as a small misfire every now and then when booting it hard and then quickly progressed to a misfire across the whole rev range except it seems to idle ok ish.

Things checked so far:

Swapped rotor arm - made no difference
Swapped Dizzy cap - made no difference
Swapped dizzy - made no difference
Swapped ht leads - made no difference
Swapped coil - made no difference
Checked gearbox and battery earths - made no difference
Swapped ignition module - made no difference

When i took the spark plugs out they were completely black and are producing a very very small intermittent spark. Is this normally down to coil?

I just want to know what else i should be checking as ive never had a problem like this before and am running out of ideas :confused:

Its running carbs now, not injection.

Paul

[pikey1986]

have you tried new plugs?

[paul91085]

Thanks for reply, i have only replaced the plugs about a month before this started happening but will get a spare set just to rule it out.

Any other ideas anyone?

[pikey1986]

possible h/g failure? might be worth having a compression test done

[paul91085]

I still have this misfire and its starting to annoy me now. Can any offer up some possible solutions or ideas?

It revs fine all the way to 5000rpm if you do it slowly, but if you plant the pedal quick, thats when the misfire occurs all the way up to 5k rpm.

Ive tried swapping various parts and doing tests, but am now stuck with what to do next :confused:

[Rich]

You say its on carbs, have you had them setup? Blocked fuel lines/filter?