HYOSUNG Aquila 250 Service Manual page 181

7-3 SERVICING INFORMATION
Complaint
Engine lacks power.
Engine overheats.
CARBURETOR
Complaint
Trouble with
starting.
Idling or low-speed
trouble.
Medium or high
speed trouble.
Overflow and fuel
level fluctuations.
Symptom and possible causes
1. Loosen of valve clearance.
2. Weakened valve springs.
3. Valve timing out of adjustment.
4. Worn piston ring or cylinder.
5. Poor seating of valves.
6. Fouled spark plug.
7. Worn camshaft.
8. Spark plug gap incorrect.
9. Clogged jets in carburetor.
10. Float-chamber fuel level out of adjustment.
11. Clogged air cleaner element.
12. Too much enging oil.
13. Defective air intake pipe.
1. Heavy carbon deposit on piston head.
2. Not enough oil in the engine.
3. Defective oil pump or clogged oil circuit.
4. Fuel level too low in float chamber.
5. Air leak from intake pipe.
6. Use of incrrect engine oil.
7. Defective oil cooler.
Symptom and possible causes
1. Starter jet is clogged.
2. Starter pipe is clogged.
3. Air leaking from a joint between starter body and carburetor.
4. Starter plunger is not operating properly.
1. Pilot jet, pilot air jet are clogged or loose.
2. Pilot outlet or bypass is clogged.
3. Starter plunger is not fully closed.
1. Main jet or main air jet is clogged.
2. Needle jet is clogged.
3. Throttle valve is not operating properly.
4. Filter is clogged.
1. Needle valve is worn or damaged.
2. Spring in needle valve is borken.
3. Float is not working properly.
4. Foreign matter has adhered to needle valve.
5. Fuel level is too high or low.
Remedy
Adjust.
Replace.
Adjust.
Replace.
Repair or replace.
Clean or replace.
Replace.
Adjust or replace.
Clean.
Adjust.
Clean.
Drain out excess oil.
Retighten or replace.
Clean.
Add oil.
Repair or clean.
Adjust.
Retighten or replace.
change.
Clean or replace.
Remedy
Clean.
Clean.
Check starter body and
carburetor for tightness,
adjust and replace gasket.
Check and adjust.
Check and clean.
Check and clean.
Check and clean.
Check and clean.
Check and clean.
Check throttle valve for
operation.
Check and clean.
Replace.
Replace.
Check and adjust.
Clean.
Adjust float height.