What to check next?

[Strika]

...To answer your ? MickC, the rex has two seperate coils, not individual coils for each cylinder like later stuff.

Well it's not the coil then otherwise it would take both of the plugs out.

Thanks mate...carb removal it is then when I get home!!!! Something to look forward to!!!

[Frank]

Another quick check is to make sure that the plug leads are connecting to the lead ends, they grenerally have what looks like the pointy end of a screw which screws into the end of the actual lead, sometimes these become corroded or even break away resulting in no or even poor spark, ( I had the same problem on my ZX7R), just another thing that you can check before you start pulling off carbies.

Sterio maybe I wasn' too clear in my explaination, but I wasn't suggesting to cross over the leads at the spark plug end alone, just swapping over the entire lead from one coil to the next, leaving the offending cylinder out to see if it still wont spark, then swapping the lead and coils over to see if the missing spark moves across and stas with the same coil/lead.

[Stereo]

Sterio maybe I wasn' too clear in my explaination, but I wasn't suggesting to cross over the leads at the spark plug end alone, just swapping over the entire lead from one coil to the next, leaving the offending cylinder out to see if it still wont spark, then swapping the lead and coils over to see if the missing spark moves across and stas with the same coil/lead.

Yeh, that would obviously work

[the kid]

...To answer your ? MickC, the rex has two seperate coils, not individual coils for each cylinder like later stuff.

Well it's not the coil then otherwise it would take both of the plugs out.

Unless its a lead or dodgy plug cap .
Dunno about the firing order on multis , but would assume that 1 coil into 2 leads must have a lost spark system ; try swopping the leads from the coil that is feeding No 1 cylinder and see if that swops the fault .

[IsleofNinja]

Is it possible to swap the coils from one side to the other or are they unique? Surely you can just unplug em and replug them into the other HT leads????? Or am I being simplistic???

To answer your ? MickC, the rex has two seperate coils, not individual coils for each cylinder like later stuff.

Yes you can swap coils over Marty - and leads as you mentioned [KISS theory applies here so don't worry].

As mentioned - I would ensure all the leads are firm and clean on the ends (no green death) and scribble a mud map of the coils / leads prior to pulling them apart (or whatever method you prefer) just to make sure you get the right sparkle to the right pot....tends to eliminate self cleaning air filter syndrome!?

It is also possible for a 2 lead coil to only fire 1 if it has an internal open circuit / damaged H.T bridge.If a multi meter don't scare you too much I can explain a few simple tests for this - your call mate.AS you said , the colder pot would obviously change when you swapped coiles if this were the case (note which side of which coil first goes to the colder cyl)

--I'd eliminate the sparkle side before ripping the carbs off too - if nothing else at least you know afterwards it'll be right for a few thousand more K's or so

[Stereo]

Taking carbs off sucks....... I would pray for an electrical problem hehe