Just been through the same troubles after a engine rebuild. My cure was as follows.
Put an new aftermarket coil on, would run fine on tick over then drop out the rear two intermittently oily wet plugs.
Checked the resistance of the cheap coil and it was a bus ride away from standard.
Rebuilt both original coils with new silicone leads and NGK caps, popped a set of iridium plugs in for good measure. Ripped out the Keyster carb rebuild kits and refreshed all with genuine mikuni
Pilot's, mains and air jets to oe spec.
Then set the float height to about 2mm lower than the gasket on the bowls.
Second kick and she was away and has never been off 4 cylinders since
Bit fluffy at low revs but I think the carbs want an accurate balance job.
Hope this helps, never give up it will come good.
Dave UK
Carbs running bad
Moderator: rztom
Re: Carbs running bad
1984 RZV500R
1985 FZ750 FN
1986 VF500 F2
2016 BMW S1000XR ( i need speed/brakes/handling
1985 FZ750 FN
1986 VF500 F2
2016 BMW S1000XR ( i need speed/brakes/handling