HYOSUNG Prima Service Manual page 125

Complaint
Engine runs
1. Excessively worn cylinder or piston rings.
poorly in high-
2. Stiff piston ring in place.
speed range.
3. Spark plug gaps to narrow.
4. Ignition not advanced sufficiently due to poorly working CDI
5. Defective magneto stator coil.
6. Float-chamber fuel level too low.
7. Clogged air cleaner element.
8. Clogged fuel hose, resulting in inadequate fuel supply to carburetor.
9. Clogged fuel cock vacuum pipe.
Dirty or heavy
1. Too much engine oil to the engine.
exhaust smoke.
2. Use of incorrect engine oil.
Engine lacks
1. Excessively worn cylinder or piston rings.
power.
2. Stiff piston ring in place.
3. Gas leaks from crankshaft oil seal.
4. Spark plug gaps incorrect.
5. Clogged jets in carburetor.
6. Float-chamber fuel level out of adjustment.
7. Clogged air cleaner element.
8. Fouled spark plug.
9. Sucking air from intake pipe.
10. Slipping or worn V-belt.
11. Damaged/worn rollers in the movable drive face.
12. Weakened movable driven face spring.
13. Too rich fuel/air mixture due to defective starter system.
Engine overheats.
1. Heavy carbon deposit on piston crown.
2. Defective oil pump or clogged oil circuit.
3. Fuel level too low in float chamber.
4. Air leakage from intake pipe.
5. Use of incorrect engine oil.
6. Use of improper spark plug.
7. Clogged exhaust pipe/muffler.
CARBURETOR
Complaint
Trouble with
1. Starter jet is clogged.
starting.
2. Air leaking from a joint between starter body and carburetor.
3. Air leaking from carburetor's joint or vacuum hose joint.
4. Starter plunger is not operating properly.
Idling or low-speed
1. Pilot jet, pilot air jet are clogged or loose.
trouble.
2. Air leaking from carburetor's joint, vacuum pipe joint, or starter.
3. Pilot outlet is clogged.
4. Starter plunger is not fully closed.
Medium or high-
1. Main jet or main air jet is clogged.
speed trouble.
2. Needle jet is clogged.
3. Fuel level is improperly set.
4. Throttle valve is not operating properly.
5. Fuel filter is clogged.
Overflow and fuel
1. Needle valve is worn or damaged.
level fluctuations.
2. Spring in deedle valve is broken.
3. Float is not working properly.
4. Foreign matter has adhered to needle valve.
5. Fuel level is too high or low.
Symptom and possible causes
& Ignition coil unit.
Symptom and possible causes
SERVICING INFORMATION 7-2
Remedy
Replace.
Replace.
Adjust.
Replace.
Replace.
Adjust or replace.
Clean
Clean, and replace.
Clean.
Check oil pump.
Change.
Replace.
Replace.
Replace.
Adjust or replace.
Clean.
Adjust or replace.
Clean.
Clean or replace.
Retighten or replace.
Replace.
Replace.
Replace.
Replace.
Clean.
Replace or clean.
Adjust or replace.
Retighten or replace.
Change.
Change.
Clean or replace.
Remedy
Clean.
Check starter body and carburetor
for tightness, and replace gasket.
Check and replace.
Check and replace.
Check and clean.
Clean and replace.
Check and clean.
Check and replace.
Check and clean.
Check and clean.
Check and replace.
Check throttle valve for operation.
Check and clean.
Replace.
Replace.
Check and adjust.
Clean.
Adjust or replace.