Photo of plugs was before I removed the carbs, cleaned them replaced the seat/valves, had the choke plunges done etc, only No 3 now remains black and sooty.
Another photo of the 'now' situation would allow a better assessment of the many changes that have happened since that photo was taken. In the picture; number 3 does not look too bad ~ rich, but on the safe side of correct!
Plug cap resistance already reported as No's 1, 2 & 4 4K8 and No 3 5K4 and this did not cause No 2 to be black and sooty when swopped.
I couldn't understand what 4K8 etc means, is that 4,800?
Air screw on No 3 has already been taken out to 2 1/2 turns with no effect. When I did the colourtune the flame colour changed from yellow at 1 1/4 to blue at 1 1/2 turns so I believe the air jet and passageway to be clear else I would not see the change in the flame colour?
This means; no effect on overall colour of plugs after a run?
If you can adjust the flame colour from full yellow to full blue in 1/4 of a turn it suggests that the fuel level / pilot screw relationship is working reasonably well within the prescribed parameters and that those two criteria are not the primary cause of an 'over-rich mixture through the rest of the range!
Can drop the No 3 needle by one groove and take air filter out, but what would I be looking at or see that would indicate/show if it is an oil fouling problem, can you kindly expand.
If its oil, you cant remove it from the equation. If its excess fuel you can artificially weaken the entire landscape by removing the air filter temporarily. If its oil it will still show up that way. If its excess fuel it will all go weak. If its both, you will get something entirely different looking!
If you can do another picture; try to resist the temptation to rub the soot / oil with a finger to see what it is. There are some critical indicators for heat range, mixture and ignition timing which rely on being able to see where the deposits are and where they stop / taper out!
Dropping the needle by one groove or half a groove on number 3, if you have those 'half' shims was a 'might as well do this at the same time' test. It might highlight a worn needle jet or jet needle or a jet needle that sticks in the jet with restricted movement.
You would need the B8 plug back in number 3, because the temp. increase with no air filter would give a misleading indication of the state of 'cleaning' of the plugs!
AL