Hi all
I had some time to test after your tips
I started by just swapping for a colder plug b7hs and it turned out pretty much the same before. And I should say looking at it again the 2nd photo I posted is closer to reality, white/grey that is. For some reason the last photos, which were taken in the sun, are chocolaty which is not true,sadly.
Second thing I tried, after putting the b6hs back on, was to check the float like Crassius suggested. I read that stock distance is 21mm.. It was more like 15mm from factory. Just for the sake of it, I set it at 21mm and it ran pretty much the same except at both WOT and high RPM/speed, above 40km/h where it would die down, like if I had hit the kill switch.. So I set it back to 15mm float level which was actually as much as it would go up..
Lastly I wanted to eliminate the chance of any air leak so I put a bunch of silicone glue around the intake manifold where the NT carb is sitting and tightened it on as much as I could and plug still looks white/grey..
This was all with needle on 2nd notch from the top.. so I am aware that is easily tuned to enrich but my idea has been from the start to get the WOT tuned first to avoid the rest of the throttle range to confound it, like as the engine warms up before testing, as I get up to speed etc..
So anyways I have gotten new jets 0.01 mm of increments from .60 to .80 so 21 different sizes and was thinking of starting with 0.75mm and a new fuel filter and clean air filter(stock) just in case.
What do you guys reckon? Also and maybe most importantly am I right to assume that a plug condition/color is cumulative from lean to rich as in a white/grey plug CAN get darker/brown but NOT the other way around?
Thanks