Engine troubleshooting information (Aprilia RS 125/3, 3 generation, 1998-2005) [Information for owner: Troubleshooting]

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 gasket leaking.	Repair or replace.
	Loose spark plug.	Tighten
	Piston broken, cracked or damaged.	Replace.
	Crankshaft seal worn.	Replace.
	No spark
	Foul spark plug.	Replace.
	Wet spark plug.	Clean and dry
	Defective coil.	Replace.
	High-tension cable interrupted or shorted.	Replace.
	Ignition system fault.	Repair or replace.
	Carburetor is receiving no fuel
	Breather hole in filler cap clogged.	Clean.
	Fuel cock clogged or defective.	Clean or replace.
	Carburetor needle valve defective.	Replace.
	Fuel tube obstructed.	Clean.
	Foul spark plug.	Clean
	Ignition system fault.	Repair or replace.
	Fuel tube obstructed.	Replace.
	Carburetor jets obstructed.	Clean.
Engine is burning oil	Oil pump out of adjustment.	Adjust.
Engine is burning oil	Crankshaft seal damaged or worn.	Replace.
Loss of engine power	Piston rings or cylinder worn.	Replace.
	Incorrect air gap between spark plug electrodes or ignition system faulty.	Adjust or replace.
	Carburetor jets obstructed.	Clean.
	Incorrect fuel level in carburetor float chamber.	Adjust.
	Air cleaner clogged.	Clean.
	Air leaking past the intake duct.	Tighten or replace.
	Engine is receiving too much oil.	Adjust the oil pump.
Engine overheats	Too much carbon build-up on piston crown.	Clean.
	Engine is receiving insufficient oil.	Adjust the oil pump.
	Oil pump faulty or oilways obstructed.	Replace or clean.
	Fuel level in carburetor float chamber too low.	Adjust.
	Air leaking into intake duct.	Tighten or replace.
	Engine oil used does not meet specification.	Use specified oil.
	Cooling system faulty.	Read radiator section.

Engine troubleshooting information (Aprilia RS125/3)