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REF.14
Fault Finding
doesn't start or is difficult to start
1 Engine
Carburettor malfunction (Chapter 3).
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 cham~
(Chapter 3).
Intake air leak. Check for loose carburettor-to-intake manifold
connections, loose or missing vacuum gauge adapter caps, or
loose carburettor tops (Chapter 3).
Engine idle speed incorrect. Turn idle adjusting screw until the
engine idles at the specified rpm (Chapter 1).
improperly tightened head bolts. Machine shop resurfacing or
Rough Idle
head replacement is necessary (Chapter 2).
0 Valve spring broken or weak. Caused by component failure or
0
Ignition malfunction (Chapter 4).
wear; the springs must be replaced (Chapter 2).
0
Idle speed incorrect (Chapter 1).
0 Valve not seating properly. This is caused by a bent valve (from
0 Carburettors not synchronlsed. Adjust carburettors with vacuum
over-rewing or improper valve adjustment), bumed valve or seat
gauge or manometer set (Chapter 1).
(improper carburation) or an accumulation of carbon deposits on
0 Carburettor malfunction (Chapter 3).
the seat (from carburation or lubrication problems). The valves
0 Fuel contaminated. The fuel can be contaminated with either dirt
must be cleaned and/or replaced and the seats serviced if
or water, or can change chemically if the machine is allowed to sit
possible (Chapter 2).
for several months or more. Drain the tank and float chambers
0 Piston ring-to-groove clewance excessive. This is caused by
excessive wear of the piston ring lands. Piston replacement is
necessary (Chapter 2).
0 Cylind« head gasket damaged. If the head is allowed to become
loose, or if 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).
0 Cylinder head warped. This is caused by ovett1eating or
Stalls after starting
0
Improper choke action. Make sure the choke linkage shaft is
getting a full stroke and staying in the out position (Chapter 3).
0
Ignition malfunction (Chapter 4).
2 Poor running at low speeds
Battery voltage low. Check and recharge battery (Chapter 8).
Spark plugs fouled, defective or worn out (Chapter 1)
Spark plug cap or HT wiring defective (Chapters 1 and 4).
Spark plug caps not making contact. Make sure they are properly
connected.
Incorrect spark plugs. Wrong type, heat range or cap
configuration. Check and install correct plugs (Chapter 1).
Ignition control defective (Chapter 4).
Pulse generator coils defective (Chapter 4).
Ignition HT coils defective (Chapter 4).
Pilot screws out of adjustment (Chapter 3).
Pilot jet or air passage clogged. Remove and overhaul the
carburettors (Chapter 3).
Air bleed holes clogged. Remove carburettor and blow out all
passages (Chapter 3).
Air filter clogged, poorly sealed or missing (Chapter 1).
Air filter housing poorly sealed. Look for cracks, holes or loose
clamps and replace or repair defective parts (Chapter 3).
Fuel level too high or too low. Check the float height (Chapter 3).
Carburettor intake manifolds loose. Check for cracks, breaks,
tears or loose clamps. Replace the rubber intake manifold joints if
split or perished (Chapter 3).
Compression low
0
Spark plugs loose. Remove the plugs and inspect their threads.
Reinstall and tighten to the specified torque (Chapter 1).
0
Cylinder head not sufficiently tightened down. If the 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 boits should be tightened to the proper torque in
the correct sequence (Chapter 2).
Fuel/air mixture incorrect
a
(continued)
e
a
0
0
(Chapter
3).
0
Intake air leak. Check
for loose
carburettor-to-intake
manifold
connections,
loose or
missing vacuum gauge adapter
caps, or
loose carburettor tops (Chapter 3).
0
Air filter clogged. Replace the air filter element (Chapter 1).
0
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).
0
Cytinder 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).
0
Piston rings wom, 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).
0
Piston rlng-to-groove clearance excessive. This is caused by
excessive wear of the piston ring lands. Piston replacement Is
necessary (Chapter 2).
0
Cytinder head gasket damaged. If the head is allowed to become
loose, or if 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 neOe68ary
(Chapter 2).
0
Cylinder head warped. This Is caused by overheating or
improperly tightened head bolts. Machine shop resurfacing or
head replacement is necessary (Chapter 2).
0
Valve spring broken or weak. Caused by component failure or
wear; the springs must be replaced (Chapter 2).
0
Valve not seating PfOPefiy. 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 deposita on
the seat (from carbu~ion or lubrication problems). The valves
must be cleaned and/or replaced and the seats serviced if
possible (Chapter 2).
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