keep it clean and it won't heat up as much, and clean your filter out every week or so with carb cleaner (take the cover off, spray the sponge/element, squeeze it out and replace.)
also, while you have the airbox off, tighten the little nut on the choke if you need to. those are notorious for loosening up.
oh yeah, don't forget about the rest of the bike. keep it greased and tuned up, like Joe said. without a motor, a beach cruiser can keep the same grease in the bearings for 100 years (though not recommended) but add a motor and grease wears out in a couple weeks.