so the plug chop would be the preferred method? i'm not sure of fuel as there is only 1 grade of petrol in ireland as far as i know.
i also tried removing the power valve restriction on my mc18 r2j and took it for a short spin about 1 km after warming up and the bike runs alot worse with this done in higher rpm. i presume this happened because it would have leaned out the mixture more.
i am going to increase the main jets 2 sizes and see how it runs then.