This is more of a General forum question, but I trust you guys in here more. I've only just started working on bikes. With the help of a friend and another guy I know, I've done work on the wheels, forks, brakes, carb, and have had the valve cover off, replaced the cam chain, primary nut fix, replaced clutch basket and plates, replaced the sprockets. My son and I just re-jetted his carb all by ourselves and the bike didn't blow up! He's starting to get into both riding and maintaining his bike. We both have a LOT to learn. So what bike would make a good project for us to learn on? Something cheap to buy, easy to get parts for (cheap), and fun to play with when we're done?