EN
CHAPTER 9
TROUBLESHOOTING
ENGINE
1. ENGINE WILL NOT START
PHENOMENON
Spark plug normal
Cylinder pressure
normal
Fuel system normal
Cylinder pressure
Fuel system normal Igniter normal
abnormal
2. ENGINE LACKS POWER
PHENOMENON
Ignition system
Fuel system
When increasing
throttle speed up
slowly or speed
down or stop the
Intake system
engine
Compression poor
16
POSSIBLE CAUSE
Oil path unpas-
sing
Fuel system
abnormal
Oil path passing
Spark normal Spark plug poor
Spark normal No spark
Spark plug
normal
POSSIBLE CAUSE
Ignition time not right
Fuel path with air
Wrong adjustment of main jet
Needle valve and main jet clogged
Oil cock clogged
Carbon deposit in the combustion chamber
Air cleaner clogged
Intake system clogged
Piston, cylinder piston ring worn
Leakage between cylinder and cylinder head
Valve gap not right
Valve sealing leakage
CORRECTION
No fuel, oil cock closed
Add fuel, open the oil cock
Air hole clogged
Clean clogged
Oil cock clogged
wash
Main jet adjusted not well,
Readjust, wash and blow
or clogged
Repair or renew
blocked.
Fuel too dirt or deteriorated Renew fuel or clear carburetor
Water in the fuel
Renew fuel and clean carburetor
Too much fuel in the
Drain fuel and clean spark plug
cylinder
Wrong fuel
Chang fuel
Carbon deposit and dirt
Clean carbon deposit and dirt
electrode
Damaged insulator
Renew spark plug
Electrode burn through.
Renew spark plug
Wrong Cap
Adjust gap
High tension coil damaged Renew high tension coil
Igniter coil damaged
Renew high tension coil
Charge magnetic or renew
enough
Piston ring worn or broken. Renew
Ring cementation
Clean carbon deposit
No washer or not tightening Add washer or tighten
Leaking from joint
Renew gasket
valve sealing poor
Lap or renew
CORRECTION
Replace ignition coil
Exhaust air
Readjustment
Clean and blow
Clean or replace
Clean carbon deposit
Clean or replace
Repair or replace
replace
Replace cylinder head gasket
Readjustment