my own RX115 used to return me 25-28 km/lit in the city or highway with its original carburettor and autolube system feeding ashless 2 stroke emarat brand oil on factory setting and BP7HS spark plug - engine had 165 psi compression when cold. Transfer and boost ports refinished to remove roughness, Reeds at 9mm stop.
I used to get about 20 to 25 on the Kawasaki KZ440 I had - come hell or high water, loved those bikes as they were dead easy to work with - but I rode them what other people call gently.
I also had an RGV250 - that was about at 6 km/lit because I only used it to run against boosted cars - lol. Even with my tall heavy self the bike would snap it front wheel up on acceleration as I shot past the 4 wheeler. It sounded like a scream from hell and went like a bat out of hell (with added mirchein on its behind)