1
. GENERAL INFORMATION
1-21
Empty fuel tank
Clogged fuel line between fuel
tank and carburetor
Clogged float oil passage
Clogged fuel tank cap breather
hole
Clogged fuel filter
Clogged fuel strainer
Faulty auto fuel
valve
Faulty spark plug
Fouled spark plug
Faulty CDI unit
Faulty pulser coil
Broken or shorted ignition coil
Broken or shorted high-tension
wire
Faulty ignition switch
Faulty starter clutch
Valve clearance too small
Improper valve and seat contact
Worn cylinder, piston and piston
rings
Leaking cylinder head gasket
Seized valve
Improper valve timing
Faulty auto bystarter
Air leaking through intake pipe
Incorrect ignition timing
Incorrectly adjusted pilot screw
Flooded carburetor
Faulty auto bystarter
Throttle valve excessively open
ENGINE LACKS POWER
Clogged air cleaner
Poor quality fuel (Restricted)
Clogged fuel tank cap breather hole
Start engine and accelerate
lightly for observation
Inspection/Adjustment
Symptom
Engine speed
increases
Engine speed does not
increase sufficiently
Check if fuel reaches
carburetor by loosening
drain screw
Remove spark plug and
install it into spark plug
cap to test spark by
connecting it to engine
ground
Spark jumps
Normal
compression
Engine does not
fire
Weak or no spark
Low or no
compression
Engine fires but
does not start
Test cylinder
compression
Start engine by follow-
ing normal starting
procedure
Fuel reaches
carburetor
Fuel does not
reach carburetor
Wet spark plug
Dry spark plug
Symptom
Remove spark plug and
inspect again
Probable Cause
