I’d stay at 50 to 1. Is the plug
actually fouled or just oily? It doesn’t look fouled.
I’d suspect a rich fuel
mixture and that of course will bring in more oil
along with the increased fuel
, good news is that no two stroke was ever hurt with a rich mix, it could just be you need to do an Italian tune up more frequently.
100 to 1 is done for reduced emissions, it’s not that the motor
needs it or will foul plugs etc, it’s that the motor
will have reduced emissions if you use half the oil.
It will tolerate it obviously but in my opinion at an increased wear rate.
Back in the day 25 to 1 wasn’t uncommon and 50 to 1 is actually pretty lean.
However having said all of that if your engine
spends its life at low RPM
and loads, then 100 to 1 will be fine.
The last days of most two strokes they had variable rate injection and at low loads they would inject extremely lean oil mixes, down well less than 100 to 1, but as you ran it harder, the amount of oil would increase drastically.
Pre-mix is of course not variable and sort of a mix it the strongest, that way your covered at WOT.
I haven’t had a two stroke in a coons age, but I believe the Enduro models spec 50 to 1 and it’s only the leisure models that are 100 to 1, and I believe that reflects the intended use model, Enduro’s are expected to be run hard and run often accumulating a lot of hours on commercial
boats, Leisure models only on some weekends on pleasure boats.
It’s not that the Leisure models are built better or out of superior metals or superior design.
So in my opinion 50 to 1 is best for the motor, but it significantly increases pollution, 100 to 1 will cause more wear, but burning half the oil reduces pollution. I guess it depends on how environmental you are, but if you are, get a good fuel injected four stroke, I bet it takes 10 of them to pollute as much as one two stroke.