Vento Phantom R4i Service Maintenance Manual page 82

Engine runs
1.
poorly in
2.
high-speed
3.
range.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Dirty or heavy 1. Too much engine oil in the engine
exhaust
smoke.
2. Defective Valve and seals
3. Worn-out valve guide/seals/leaks of valves
4. Weakened valve springs.
5. Worn piston rings or cylinder
6. Worn Valves or stems
7. Worn oil rings side rails
Engine lacks 1. Excessively worn cylinder or piston rings.
power. 2. Sticky piston ring in grooves.
3. Compression leaks from valves & gaskets.
4. Spark plug gaps incorrect.
5. Clogged air cleaner element.
6. Float-chamber fuel level out of adjustment.
7. Fouled spark plug,
8. Sucking air from intake pipe.
9. Slipping or worn V-belt.
10. Damaged/worn rollers in the movable drive face.
11. Weak movable driven face spring.
12. Too rich fuel/air mixture due to defective starter system.
Engine over 1. Heavy carbon deposits on piston crown.
2. Defective oil pump or clogged oil circuit.
heats.
3. Fuel level too low in float chamber.
4. Air leakage from intake pipe.
VENTO MOTORCYCLES
5. Not enough oil in the engine
6. Used incorrect engine oil
Excessively worn cylinder or piston rings.
Sticky piston ring in grooves.
Spark plug gaps too less.
Ignition not advanced sufficiently due to poorly
working CDI & ignition coil unit.
Defective magneto stator coil.
Float-chamber fuel level too low.
Clogged air cleaner element.
Clogged fuel hose, resulting in inadequate fuel
supply to carburetor.
Clogged fuel cock vacuum pipe.
Weakened valve springs.
Worn camshaft.
Valve Timing out of adjustment.
Too wide spark plug gap.
Defective Ignition coil
Defective Pickup coil or CDI
Too low float chamber fuel level
Rev no.01/ page 82of 84
Replace.
Replace or clean.
Adjust.
Replace.
Replace.
Adjust or replace.
Clean.
Clean and prime.
Clean.
Replace.
Replace.
Adjust.
Adjust.
Replace CDI unit.
Replace.
Adjust.
Check with Oil level
gauge, drain excessive
oil
Check & Replace.
Check & Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace & repair.
Adjust or replace.
Clean.
Adjust or replace.
Clean.
Clean or replace the
gaskets.
Replace.
Replace.
Replace.
Replace.
Clean.
Replace and clean.
Adjust or replace.
Retighten/replace
gaskets.
Add specified oil.
Change & use specified