What to do when ex bf is asking for sex?

ill try to keep this short. we were together for almost 4 years and been broken up for close to 2 years. we broke up because he didnt love me anymore and recently became friends again. we hang out and text eachother. now he is starting to ask for sexual favors. i still like him but what is the best way to go about this? i highly doubt we will ever date again but still what should i do? i dont want him thinking im easy and will be there for a booty call whenever he wants and i definatly deserve some respect how do i get that across without sounding like a b**ch?