RE: saito rebuild?
Very do-able at home. You'll need just a couple hex wenches and a small screwdriver. I use a small surgical clamp to handle the tiny things like valve springs and the retainers, but a pair of tweezers would work fine. If you're going to remove the crank, you'll need a small puller to get the prop drive washer off. Take your time and make notes as you disassemble it so you know how to put it back together. If you have a problem just ask here.
Paul