Fouling plugs

[rupecopp]

Hi,

I brought a 2002 ec200 a couple of months ago. I took it for a couple of rides on the beach to get used to it.

Since then I've taken it trial ridding, and when I go through the slow sections or have idling for a while it fouls plugs, leaving them very wet.

I made a couple of mistakes I went from 40:1 (last owners recomendation)synth pre mix to 50:1 to try and solve the problem. I then learnt this was wrong so I back running 40:1. I aslo wasn't happy with the way it was idling so I turned the black plastic screw with the spring till I was happy it was faster. What I didn't do was adjust the air screw, I've since done this but I'm not 100% I've done it right, any tips?

I'm also thinking that does the black plastic screw mess up more than just the idle?

Thanks