Hi, I'm sure Motul 710 at 50:1 is fine.
So you dropped to a 40 Pilot Jet, that will only really effect the mixture at idle and the initial throttle opening. So if that's all you've changed you probably haven't noticed much difference when riding.
Have you been able to change the needle yet or are you still on the N1EF? From my experience and what the majority of others say, the N1EF is always too rich.
Once you try a leaner/fatter needle you'll feel a change and the amount of spooge will decrease.
The plug looks black and oily so definitely not dangerously lean.
To be honest, plug readings are more useful for checking the Main Jet size by completing a 'Plug Chop' procedure - involves cutting the ignition whilst running at Wide Open Throttle, at high RPM, under load. Needs a long straight road/track. Google it you need precise instructions.
All the best, Dave.
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