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Fault finding
REF05
4 Overheating
Engine overheats
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liquid-cooled engines
Coolant level low. Check and add coolant (Chapter 1).
Leak in cooling system. Check cooling system hoses and radiator
for leaks and other damage. Repair or renew parts as necessary
(Chapter 3).
Thermostat sticking open or closed. Check and renew (Chapter 3).
Coolant passages clogged. Drain and flush the entire system, then
refill with fresh coolant.
Water pump defective. Remove the pump and check the
components (Chapter 3).
Clogged radiator fins. Clean them by blowing compressed air
through the fins from the rear of the radiator.
Engine overheats
-
air-cooled engines
Air cooling ducts blocked or incorrectly fitted.
Problem with cooling fan.
Fldng lncomct
Spark plug fouled, defective or worn out. See Chapter 1 for spark
plug maintenance.
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Incorrect spark plug.
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CDI unit defective (Chapter 5).
Faulty ignition HT coil (Chapter 5).
Fuel/alr mixture lncomct
Main jet clogged. Dirt, water or other contaminants can clog the
main jet. Clean the fuel tap filter and the carburettor (Chapter 4).
Main jet wrong size. The standard jetting is for sea level
atmospheric pressure and oxygen content.
Air bleed holes clogged. Remove and overhaul carburettor
(Chapter 4).
Air filter clogged, poorly sealed, or missing (Chapter 1).
Transmission problems
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No drive to rear wheel
Drive belt broken (Chapter 2C).
Clutch not engaging (Chapter 2C).
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Clutch friction material or drum excessively worn (Chapter 2C).
Transmission noise or vibration
Bearings worn. Also includes the possibility that the shafts are
worn. Overhaul the transmission (Chapter 2C).
Gears worn or chipped (Chapter 2C)
Clutch drum wom unevenly (Chapter 2C).
Clutch pulley or variator pulley out of alignment (Chapter 2C).
Bent or damaged transmission shaft (Chapter
X).
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Loose clutch nut or variator nut (Chapter 2C).
Air filter housing or duct poorly sealed. Look for cracks, holes or
loose clamps or screws, and renew or repair defective parts.
Carburettor inlet manifold loose. Check for cracks, breaks,
damaged gaskets or loose clamps.
Compression too hlgh
Carbon build-up in the cylinder head. Decarbonise the cylinder
head (Chapter 1).
Improperly machined head surface.
Engine load excessive
Clutch slipping, drive belt wom, or speed governor faulty
(Chapter 2C).
Brakes dragging. On disc brakes, usually caused by debris which
has entered the brake piston seals, or from a warped disc or bent
axle. On drum brakes, cable out of adjustment, shoe return spring
broken. Repair as necessary (Chapter 8).
Lubrication Inadequate
Oil pump out of adjustment. Adjust pump cable on models so
equipped (Chapter 1).
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Poor quality oil or incorrect viscosity or type. Oil is rated not only
according to viscosity but also according to type. Some oils are
not rated high enough for use in this engine. Check the
Specifications section, then drain the oil tank and refill with the
correct oil (Chapter 1).
Miscellaneous causes
Modification to exhaust system. Most aftermarket exhaust
systems cause the engine to run leaner, which make them run
hotter. When installing an accessory exhaust system, always
obtain advice on rejetting the carburettor.
Poor performance
Variator rollers worn or insufficiently greased (Chapter 2C).
Weak or broken clutch pulley spring (Chapter 2C).
Clutch or drum excessively worn (Chapter 2C).
Grease on clutch friction material (Chapter 2C).
Drive belt excessively worn (Chapter 2C).
Clutch not disengaging completely
Weak or broken clutch springs (Chapter 2C).
Engine idle speed too high (Chapter 1).
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