30kms per litre or 71mpg(us gallon) 85mpg(imperial gallon) mixed road highway. 25kms per litre 59mpg (us gallon) 70mpg (imperial gallon) single track.

A pleasant surprise, I have just installed a FMF Q4 slip on and a Factory pro jet kit. After two days tuning (I'm sure I could re&are the carb blindfolded by now) I went for a real good rip today. Not only does my bike run awesome it gets better milage, more power especially down low. I climbed some single track today and lugged it down way more. So much more responsive and crisp with real usable tourque down low.
If you do nothing else to your KLX I strongly recommend doing this mod. Did not remove snorkel or air box lid. Stock air filter element only a slip on pipe and a jet kit. I wouldn't wast a lot of time with Dinojet kits. The Factory Pro kit comes with a bigger pilot jet as well as main jets. That is the secret.

38 pilot jet from 35, 120 main jet, second clip on the rod and 2.5 turns on the fuel screw. Factory float adjustment. Found no need to adjust it.

Be sure to follow the factory pro cv carb tuning instructions. Take your time. It will pay off in spades later.

 

What kit did you buy? I don't see anything listed for the klx250s on their website.

 

Factory Pro K03-10. I also installed the extended fuel screw. Awesome combo. Was going to try quiet core insert but don't want to loose any performance.