Starter motor doesn't rotate
- Engine kill switch OFF.
- Fuse blown. Check main fuse and starter circuit fuse (Chapter 9).
- Battery voltage low. Check and recharge battery (Chapter 9).
- Starter motor defective. Make sure the wiring to the starter is secure. Make sure the starter relay clicks when the start button is pushed. If the relay clicks, then the fault is in the wiring or motor.
- Starter relay faulty. Check it according to the procedure in Chapter 9.
- Starter button not contacting. The contacts could be wet, corroded or dirty. Disassemble and clean the switch (Chapter 9).
- Wiring open or shorted. Check all wiring connections and harnesses to make sure that they are dry. tight and not corroded. Also check for broken or frayed wires that can cause a short to ground (earth) (see wiring diagram, Chapter 9).
- Ignition (main) switch defective. Check the switch according to the procedure in Chapter 9. Replace the switch with a new one if it is defective.
- Engine kill switch defective. Check for wet. dirty or corroded contacts. Clean or replace the switch as necessary (Chapter 9).
- Faulty neutral, side stand (where fitted) or clutch switch. Check the wiring to each switch and the switch itself according to the procedures in Chapter 9.
Starter motor rotates but engine does not turn over
- Starter clutch defective. Inspect and repair or renew (Chapter 2).
- Damaged idle or starter gears. Inspect and renew the damaged parts (Chapter 2).
- Starter works but engine won't turn over (seized)
- Seized engine caused by one or more internally damaged components. Failure due to wear, abuse or lack of lubrication. Damage can include seized valves, rockers, camshafts, pistons, crankshaft, connecting rod bearings, or transmission gears or bearings. Refer to Chapter 2 for engine disassembly.
No fuel flow
- No fuel in tank.
- Fuel tank breather hose obstructed.
- Fuel tap strainer, or in-line filter (XRV models), clogged. Remove the tap and clean it and the filter (Chapter 4).
- Fuel tap vacuum hose split or detached (XL models). Check the hose.
- Fuel tap diaphragm split (XL models). Remove the tap and check the diaphragm (Chapter 4).
- Fuel line clogged. Pull the fuel line loose and carefully blow through it.
- Float needle valve clogged. For both of the valves to be clogged, either a very bad batch of fuel with an unusual additive has been used, or some other foreign material has entered the tank. Many times after a machine has been stored for many months without running, the fuel turns to a varnish-like liquid and forms deposits on the inlet needle valves and jets. The carburettors should be removed and overhauled if draining the float chambers doesn't solve the problem.
- Fuel pump faulty (XRV models). Check the fuel pump flow and renew the pump if necessary (Chapter 4).
Engine flooded
- Float height too high. Check as described in Chapter 4.
- Float needle valve worn or stuck open. A piece of dirt, rust or other debris can cause the valve to seat improperly, causing excess fuel to be admitted to the float chamber. In this case, the float chamber should be cleaned and the needle valve and seat inspected. If the needle and seat are worn, then the leaking will persist and the parts should be replaced with new ones (Chapter 4).
- Starting technique incorrect. Under normal circumstances (i.e., if all the carburettor functions are sound) the machine should start with little or no throttle. When the engine is cold, the choke should be operated and the engine started without opening the throttle. When the engine is at operating temperature, only a very slight amount of throttle should be necessary. If the engine is flooded, turn the fuel tap OFF or disconnect the vacuum hose (according to model - see Chapter 4) and hold the throttle open while cranking the engine. This will allow additional air to reach the cylinders. Remember to turn the fuel tap back ON or attach the vacuum hose.
No spark or weak spark
- Ignition switch OFF.
- Engine kill switch turned to the OFF position.
- Battery voltage low. Check and recharge the battery as necessary (Chapter 9).
- Spark plugs dirty, defective or worn out. Locate reason for fouled plugs using spark plug condition chart and follow the plug maintenance procedures (Chapter 1).
- Spark plug caps or secondary (HT) wiring faulty. Check condition. Renew either or both components if cracks or deterioration are evident (Chapter 5).
- Spark plug caps not making good contact. Make sure that the plug caps fit snugly over the plug ends.
- Ignition control unit defective. Check the unit (Chapter 5).
- Pulse generator coil defective. Check the unit (Chapter 5).
- Ignition HT coils defective. Check the coils (Chapter 5).
- Ignition or kill switch shorted. This is usually caused by water, corrosion, damage or excessive wear. The switches can be disassembled and cleaned with electrical contact cleaner. If cleaning does not help, renew the switches (Chapter 9).
- Wiring shorted or broken between:
- a) Ignition (main) switch and engine kill switch (or blown fuse)
- b) Ignition control unit and engine kill switch
- c) Ignition control unit and ignition HT coils
- d) Ignition HT coils and spark plugs
- e) Ignition control unit and pulse generator coil. Make sure that all wiring connections are clean, dry and tight. Look for chafed and broken wires (Chapters 5 and 9).
Compression low
- Spark plugs loose. Remove the plugs and inspect their threads. Reinstall and tighten to the specified torque (Chapter 1).
- Cylinder head(s) not sufficiently tightened down. If a cylinder head is suspected of being loose, then there's a chance that the gasket or head is damaged if the problem has persisted for any length of time. The head nuts/bolts should be tightened to the proper torque in the correct sequence (Chapter 2).
- Improper valve clearance. This means that the valve is not closing completely and compression pressure is leaking past the valve. Check and adjust the valve clearances (Chapter 1).
- Cylinder and/or piston worn. Excessive wear will cause compression pressure to leak past the rings. This is usually accompanied by worn rings as well. A top-end overhaul is necessary (Chapter 2).
- Piston rings worn, weak, broken, or sticking. Broken or sticking piston rings usually indicate a lubrication or carburation problem that causes excess carbon deposits or seizures to form on the pistons and rings. Top-end overhaul is necessary (Chapter 2).
- Piston ring-to-groove clearance excessive. This is caused by excessive wear of the piston ring lands. Piston replacement is necessary (Chapter 2).
- Cylinder head gasket(s) damaged. If a head is allowed to become loose, or It excessive carbon build-up on the piston crown and combustion chamber causes extremely high compression, the head gasket may leak. Retorquing the head is not always sufficient to restore the seal, so gasket replacement is necessary (Chapter 2).
- Cylinder head(s) warped. This is caused by overheating or improperly tightened head nuts/bolts. Machine shop resurfacing or head replacement is necessary (Chapter 2).
- Valve spring broken or weak. Caused by component failure or wear: the springs must be renewed (Chapter 2).
- Valve not seating properly. This is caused by a bent valve (from over-revving or improper valve adjustment), burned valve or seat (improper carburation) or an accumulation of carbon deposits on the seat (from carburation or lubrication problems). The valves must be cleaned and/or replaced and the seats serviced if possible (Chapter 2).
Stalls after starting
- Improper choke action. Make sure the choke plungers are staying in the out position (Chapter 4).
- Ignition malfunction (Chapter 5).
- Carburettor malfunction (Chapter 4).
- Fuel contaminated. The fuel can be contaminated with either dirt or water, or can change chemically if the machine is allowed to sit for several months or more. Drain the tank and float chambers (Chapter 4).
- Intake air leak. Check for loose carburettor-to-intake manifold connections, loose vacuum gauge adapter screws or hoses (as applicable), or loose carburettor tops (Chapter 4).
- Engine idle speed incorrect. Turn idle adjusting screw until the engine idles at the specified rpm (Chapter 1).
Rough idle
- Ignition malfunction (Chapter 5).
- Idle speed incorrect (Chapter 1).
- Carburettors not synchronised. Adjust carburettors with vacuum gauge or manometer set as described in Chapter 1.
- Pilot jet or air passage clogged. Remove and overhaul the carburettors, and check jet sizes (Chapter 4).
- Fuel contaminated. The fuel can be contaminated with either dirt or water, or can change chemically if the machine is allowed to sit for several months or more. Drain the tank and float chambers (Chapter 4).
- Intake air leak. Check for loose carburettor-to-intake manifold connections, loose vacuum gauge adapter screws or hoses (as applicable), or loose carburettor tops (Chapter 4).
- Air filter clogged. Replace the air filter element (Chapter1).