Yamaha YTZ250S 1986 User Manual

II APPENDICES
TROUBLESHOOTING GUIDE
Engine is hard to start or does not start.
Ignition System
Possible Cause
Remedy
1.
Spark plug is wet.
• Clean or replace
2. Ignition coil is faulty.
• Replace
3. C.D.I. unit is faulty.
• Replace
4. C.D.I. magneto is faulty (Pulser
• Replace
coil, source coil)
5. Ignition timing is incorrect.
• Adjust
6. Wire is broken, shorted or dis-
• Repair, replace or connect
connected.
7. Engine stop switch is shorted.
• Repair or replace
Compression System
Possible
Cause Remedy
1.
Piston rings are sticking or worn.
• Replace
2. Cylinder or piston is worn or
• Repair or replace
scratched.
3. Compression leaks passing cylinder
• Replace (or
repa i r)
head gasket. (Head is distoreted).
4. Crankshaft side oil seal is faulty.
• Replace
5. Air leaks through crankcase
• Repair
sealing surfaces.
Air/Fuel System
Possible
Cause Remedy
1. Carburetor pilot jet is clogged.
•
Clean
2. Fuel petcock or pipe is clogged.
• Clean
3. Float valve is faulty.
• Replace (remove gasoline from
(Float height
is too high or too low.) crankcase)
4. Reed valve is broken or deformed.
• Replace
5. Fuel tank filler cap or carburetor
• Clean
brather pipe is clogged.
6. Air screw is improperly adjusted.
• Adjust
7. Fuel is deteriorated.
• Repalce
8. Oil-gas mixing ratio is incorrect.
• Replace
9. Air leakes through carburetor joints.
• Retighten or replace gasket
6-1

Yamaha YTZ250S 1986 Specifications

General

Brand	Yamaha
Model	YTZ250S 1986
Category	Motorcycle
Language	English