This volume (No. 6004) covers: engine, carburetor, electrical system, and chassis of 50cc, 80cc, and 125cc models. Chapters and topics in this book include: - In top condition? How to properly buy and sell used 50cc, 80cc, or 125cc models. With everything that the TÜV checks every two years. - The right tools for the hobby and home workshop. - Adjustments, maintenance, regular servicing. - All about tires. - Maintaining, caring for, and repairing disc and drum brakes. - Adjusting suspension, disassembling the front fork, changing fork oil. - Adjusting steering, replacing steering bearings. - Maintaining air filters, cleaning and adjusting carburetors. - The right oil for two-stroke and four-stroke engines. - Performing an oil change yourself. - Maintaining and caring for spark plugs. - Ignition system: adjusting, troubleshooting, finding and fixing issues. - What to consider when charging the battery. - Battery charging system: troubleshooting and fixing. - Lights, horn, and fuses.