A thing like this already exists. It's called: Honda Super Cub!
Grand Daddy of our CD70s & Chonda 70s! And spiritual father of CD100s and most Chonda 100s that basically use either stroked or bored up CD70 motors! A proven, reliable, indestructable yet economical motorcycle. HANDS DOWN!
Honda only made 2 great bikes in it's entire history: CB750 that kicked inline-4 trend back in late 60's and THIS LITTLE CRITTER!!! The bike that made Honda what it is today...