1979 Z1000st running rich on one cylinder

[Pedd]

My mate has a 1979 Z1000st the bike is running rough as fook, its all down to cylinder no 3 which is running rich (black sooty plug) no matter what we do we cant get this problem sorted, heres what we have done so far.


new plug
cleaned carb and reset float height
swapped all carb internals over with carb from good running cylinder
reset carb to defaults (air mixture screw)
checked coils with meter (reads fine)
swapped coils from known working good side
checked coil pickups
checked compression (all cylinders are roughly the same)
Balanced carbs


the bike still fouls plug no 3 and runs rough as fook. The above is the limit of my knowledge so thought I may aswell ask here as to what to look at next.
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Dont Click HERE
Current modes of transport = 125 superdream (in bits atm), 1978 GS750 chop, bandit 600(main one), 1982 bmw r100rs,
cx500 trike (hey its fun) oh and the car to ferry the missus and dogs around

[Pedd]

yeah defo sooty, its dry not wet. No smoking either
____________________
Dont Click HERE
Current modes of transport = 125 superdream (in bits atm), 1978 GS750 chop, bandit 600(main one), 1982 bmw r100rs,
cx500 trike (hey its fun) oh and the car to ferry the missus and dogs around

[Pedd]

forgot to say its slide carbs, had a look but we cant see any, whats the best way to check for cracks ???


oh and forgot to say its the transistorized version not the points version and its a shaft drive aswell.
____________________
Dont Click HERE
Current modes of transport = 125 superdream (in bits atm), 1978 GS750 chop, bandit 600(main one), 1982 bmw r100rs,
cx500 trike (hey its fun) oh and the car to ferry the missus and dogs around

[temeluchus]

[Pedd]

Ill nip over there later and get a pic of the plug if I can, the emulsion tubes where swapped over from one of the other carbs and the problem still stays.

will have a go tomorrow hopefully with the torch, Compression tests where just tried dry I think, will confirm with him later. What diff would it make tho, I know wet if compression increases then more than likely rings but surely if all cylinders test near as damn it the same dry it should be fine as the problem is only one cylinder.


Cheers for hte hints tho fella's
____________________
Dont Click HERE
Current modes of transport = 125 superdream (in bits atm), 1978 GS750 chop, bandit 600(main one), 1982 bmw r100rs,
cx500 trike (hey its fun) oh and the car to ferry the missus and dogs around