Couple three docs say unofficially I have torn tendons in the top of my foot, which explains why it takes so long to heal and that I can still windsurf just fine, but have trouble snowboarding and loading that ankle.
My KX-420 actually got about 30 mpg. But it also holeshot 80% of the starts, so I couldn't complain. My bud's Maico490 actually got worse mileage. My roomate's CR-450 got about 50 mpg. The Husky390WR I had for 4 months barely got 30. My BSA500MX got about 65 mpg, used the old Husky aluminum 1.6 gallon tank and did fine on the sand beach rides for over 1.5 hours, including keystone cop chase scenes running from the SanFrancisco City Cops.
Still, as I said, adding fork and shock oil, tranny and water coolant, + the minimum 3 gallon tank (presume you ride in the desert), you're looking at 235lbs. minimum.
Maybe run a slow throttle to start....or don't take a handful of throttle.