cb650z miss firing

[itsdave]

So yesterday I was riding around and noticed one of my pistons was not firing.
So I changed all of the spark plugs and it seemed to be sorted but it seems to haveggone back to how it was I think. Now it has all new sparks.what could be wrong? Any suggestions many thabks
Suppose to be going to Cambridge on Tuesday.
Oh I was on motorways and A roads today if that makes a difference.

Thanks again.

Its.
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Project cg125 current bike cbr600f sport white+ black watch out for me in central London.

[RhynoCZ]

Are you sure it's not a fuel starvation problem? Also change spark leads and if nothing then I'd say one of your ignition coils is faulty. Did the bike get wet before it happened?
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[itsdave]

I was bumping it for a bit and it was fine then when I got the battery fitted properly this happens.
Thanks for the ideas I will check the carbs and everything else.

Its.
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Project cg125 current bike cbr600f sport white+ black watch out for me in central London.

[itsdave]

I have just startd her up. Reved and it started to fire all 4 but put hand behind exhaust and specs of what look like oil hir my hand. Not loads just a little.

Its.
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Project cg125 current bike cbr600f sport white+ black watch out for me in central London.

[moonzoomer]

The HT coils on this model are not good, they tend to split their outer casing so a visual check usually confirms the faulty coil ( there are only 2) to confirm the coil fault switch over the ignition input wire from one coil to the other, if the bike misfires on the other 2 cylinders then the coil is faulty and needs to be replaced but do not use S/H items as these are usually knackered or on their way out.