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Fault finding
REF.3
1 Engine doesn't start or is difficult to start (continued)
Engine flooded
Float needle valve wom or stuck open. A
psa
d
+ -
-st
a
other debris can jam the valve open, cauwq
-
+ s
B
. u l
into the float chamber. In this case, the
fb?
m
W
be
cleaned and the needle valve and seat
- -
'
-ec!k
and seat are worn, then the leaking will p
e
~
~
rc
' t
r a ~ s
should be replaced with new ones ( C h w ~
L
No spark or weak spark
Battery voltage low. Check and recharge
tcr
s
, - 1 y
(Chapter 9).
Spark plug dirty, defective or wom out Locdr
w
*brlsd
plug using spark plug condition chart at
tCT m~
9 tb
and follow the plug maintenance p r o c e c b s
'
-
Condition is especially applicable to
--the
oily nature of their lubrication system.
Spark plug cap or secondary (HT) wiring tab.. h B
rmdjiDn.
Renew either or both components if mads w
ae
evident (Chapter 5).
Spark plug cap not making good contact Cbk
rrr
w ' h c plug
cap fits snugly over the plug end.
CDI unit defective. Refer to Chapter 5 for
daa
Pulse generator coil or source coil
M
h
referring to Chapter 5 for details.
lgnition HT coil defective. Check the
col
t
5.
lgnition switch shorted. This is usually
sr
w
- .
damage or excessive wear. Where
p o s b e
j s a r a t
?e
switch and clean the contacts, o t h e m -mm
V
-
(Chapter 9).
Wiring shorted or broken. Make sure
that
uq
are clean, dry and tight. Look for chafed
sr
-
n
(Chapters 5 and 9).
Compression low
Spark plug loose. Remove the plug and
iQk
fs
(Chapter 1).
Cylinder head not sufficiently tightened
m-
fh
? m d
is suspected of being loose, then there's a
z m u ~
fa
tr
gasket
or head is damaged if the problem has
-
v
rr
of
time. The head bolts should be tightenec ?z
3 ~ ? r
rn
the correct sequence (Chapter 2).
Low crankcase compression due to wr
9
rJr
Condition will upset the fuel/air mixtue Ebar tt
5
(Chapter 2).
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 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 renewal is
necessary (Chapter 2).
Cylinder head gasket damaged. If a 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. Renew the gasket (Chapter 2).
Cylinder head warped. This is caused by overheating or
improperly tightened head bolts. Machine shop resurfacing or
head renewal is necessary (Chapter 2).
Stalls affer starting
Faulty automatic choke. Check connections and movement
(Chapter 4).
lgnition 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 carburettor
(Chapter 4).
lnlet air leak. Check for loose carburettor-to-inlet manifold
connection, loose carburettor top (Chapter 4).
Engine idle speed incorrect. Tum idle adjusting screw until the
engine idles at the specified rpm (Chapter 1).
Rough Idle
lgnition malfunction (Chapter 5).
Idle speed incorrect (Chapter 1).
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 old fuel and refill with fresh
fuel of the recommended grade (Chapter 4).
lnlet air leak. Check for loose carburettor-to-inlet manifold
connection, loose carburettor top (Chapter 4).
Air filter clogged. Clean the air filter element (Chapter 1).
2 Poor running at law speeds
Spark weak
Fuel/air mixture incorrect
Battery voltage low. Check and rechagc
Z?nQI 9.
Spark plug fouled, defective or wom
as-
- r
'
f o r
spark plug maintenance.
Spark plug cap or HT wiring defectha Rlbr
*
and 5
for details on the ignition system.
Spark plug cap not making contact
Incorrect spark plug. Wrong type, heat
s
a l t g v a t i a n .
Check and install correct plug listed h
- '
CDI unit defective (Chapter 5).
Pulse generator coil defective (ChaptsSC
lgnition HT coil defective (Chapter
5 ) .
Pilot screw out of adjustment (Chapter 4).
Pilot jet or air passage clogged. Remove and overhaul the
carburettor (Chapter 4).
Air bleed hole clogged. Remove carburettor and blow out all
passages (Chapter 4).
Air filter clogged, poorly sealed or missing (Chapter 1).
Air filter housing poorly sealed. Look for cracks, holes or loose
screws and replace or repair defective parts.
Carburettor inlet manifold loose. Check for cracks, breaks,
damaged gaskets or loose clamps.
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