Diagnosis and troubleshooting of motorcycle Aprilia RS125 3 (RS-series, 1999-2005)

Engine troubleshooting information
Trouble Symptom and possible causes Remedy Engine does not start or is difficult to start Low compression Cylinder or piston rings exceedingly worn. Replace. Piston ring sticking in its groove. Repair or replace. Crankcase, cylinder or cylinder head...

Carburetor troubleshooting information
Trouble Symptom and possible causes Remedy Difficulties on starting Starter jet obstructed. Clean. Starter duct obstructed. Clean. Air leaking past the gasket between cold-start body and carburetor. Check and tighten. Cold-start shutter is...

Radiator troubleshooting information
Trouble Symptom and possible causes Remedy Engine overheats Coolant insufficient. Top up. Radiator fins obstructed by dirt or debris. Clean. Thermostat faulty, jammed in the closed position. Replace. Coolant passages obstructed. Clean. Air in the...

Electrical system troubleshooting information
Trouble Symptom and possible causes Remedy Spark plugs develop exceeding carbon buildup too quickly Carburetion too rich. Adjust carburetor. Idling speed set too high. Adjust carburetor. Fuel does not meet specification. Change fuel. Air cleaner...

Battery troubleshooting information
Trouble Symptom and possible causes Remedy Battery runs flat quickly Charge system faulty. Check generator, regulator/rectifier, circuit connections and rectify to obtain proper charge Battery was overcharged and battery cells lost much of their...

Brakes troubleshooting information
Trouble Symptom and possible causes Remedy Loss of braking Brake hydraulic system leaking. Repair or replace. Brake pads worn. Replace. Contact surfaces of brake pads contaminated with oil. Replace. Brake discs worn. Replace. Air in the hydraulic...

Chassis troubleshooting information
Trouble Symptom and possible causes Remedy Hard steering Steering adjusting ring nut overtightened. Adjust. Steering bearing damaged. Replace. Steering stem distorted. Replace. Tyre underinflated. Adjust. Handlebars shake Uneven front fork settings....