Just bought my son a used JR50 for his 5th b-day, and was wondering what maintenace I should perform. I checked/replaced the brake shoes and adjusted the cables, changed tranny fluid, and basically gave it a once-over. I'm a streetbike 4-stroke guy tho, so I have no idea what to check engine wise on one of these things. Plug is a nice tan color, but other than that I have no clue. Any help?? Thanks in advance.