Perform Preventive Maintenance and Periodic Servicing of Motorcycle/Small Engines
Preventive Maintenance and Periodic Servicing
This domain tests scheduled maintenance: what is checked, at what interval, and what the correct adjustment is. It is about preventing failures, not repairing them.
Core rules
- Pre-ride checks: tire pressure and tread, brake lever and pedal feel, lights, horn, fuel level, oil level, chain slack, and leaks.
- First service around 500–1,000 km: change oil, check valve clearance, tighten head bolts, adjust chain and brakes, check fasteners.
- Then every 3,000–4,000 km or as the manual states: oil and filter, air filter, spark plug, valve clearance (commonly 0.05–0.10 mm intake and 0.08–0.12 mm exhaust on small engines - follow the manual), carburetor idle, battery electrolyte and terminals, cables, and brake shoes or pads.
- Chain slack is usually 20–30 mm at the tightest point; adjust at the rear axle and align the wheel with the swingarm marks.
- Set valve clearance with the engine cold and the piston at TDC on the compression stroke, both valves closed and the "T" mark aligned.
- Record every service: date, odometer, parts used, findings.
Worked example
A 110 cc underbone arrives at 6,000 km with a slightly rough idle. The technician warms and drains the engine, replaces the oil filter, cleans the air filter, inspects the plug (light tan = good), checks valve clearance cold at 0.08 mm intake and 0.10 mm exhaust, sets chain slack to 25 mm, adjusts the rear brake, sets tire pressures, and road-tests. Reasoning: each item follows the manual's interval and specification, and the rough idle is addressed by valve and idle adjustment before any parts are replaced.
Traps
Overfilling oil (foaming, seal leaks); over-tightening the chain (wheel bearing and countershaft wear); setting valves on a hot engine; reusing a crush washer and causing a leak; skipping the road test so a misadjustment leaves the shop.