I've got a Honda CB600S (CB600F II) from 2001. When I bought it, the carb was worn, causing it to run way too rich. Fuel consumption was absolutely terrible, see my previous post: Honda CB600S 2001 carb rebuild
I've since managed to get my hands on a replacement carb, and it runs great again. But I'm seeing room for improvement.
When I'm driving a lot of highway, my mileage is 23.5km/l (55mpg). When driving my regular commute with sustained RPM (not accelerating) around 3k, it drops to 13.5km/l (32mpg). When doing my commute with sustained RPM around 6k, it's roughly 17km/l (40mpg). I'm guessing this has to do with the temperature the engine reaches. My commute is quite short, 12km, of which the first 4 is city driving (<50km/h, <31mph).
I know this carb has slightly bigger main jets than stock, K108 instead of K105.
How can I best tune my carb for shorter trips? Is it worth switching to K105s again? Kit-needles at lower settings? Just run at 6K RPM? Engine block heaters? I'm willing to hand in a bit of performance.