My Honda CB shine have serious milage problem, i've change everthing l

My Honda CB shine have serious milage problem, i've change everthing like air filter, spark plug, mobil etc. But still the milage is only 35km/L. Even the honda showroom service center persons are saying that there is no problem with the bike. So please suggest me how can i improve the milage of my bike. Please help me. Thanks

Need help or advice? Ask your question and get help from experts