So i think most people will have aftermarket slip-ons on their 250's without any other modifications, i myself have a little shorty can on and have noticed what i first thought was richness at higher revs is most probably not richness but the engine running leaner, especially at 16k - redline holding wot at higher speeds. i know there are some little tricks to make it run richer, most popular being shimming the jet needle, but that wont do much at wot as it is fully open by that time anyway, same with drilling another hole on the slide. I was thinking of changing the main jets but its running great at lower revs and changing the main jet might cause it to run way to rich down low which is where it is sitting the majority of the time and just make it a pig for normal conditions. how is it possible to rectify this, especially when these bikes are so moody when it comes to fueling.
i have looked at the plugs afew times, they seem fine if not slightly rich. as i said its just in the very high rpms where it doesnt pull as hard as it should or does with the stock exhaust.
