maybe a stupid question but hey doesn’t cost anything to ask, as I got my rg from Japan (1986 mk111) I’m only assuming from factory they may of used different jetting to us here in Oz. Does anyone have factory jet sizes for us here in Oz and also what plug I should be using? At the moment as delivered from Japan it using a NGK BR8ES?
Most bikes directly imported from the northern hemisphere run slightly rich as the air is denser there, but seeing as how the fuel quality has deteriorated from the 1980's then the jetting may be about right. As always, try it and see.