Yamaha YZ250 2021 User Manual

TROUBLESHOOTING
7-8
EAM30512
TROUBLESHOOTING OF COOLING SYSTEM
Symptom Possible cause Actions
Overheating
Carbon buildup in piston head and
combustion chamber
Clean the piston head and com-
bustion chamber.
Clogged engine cooling water
passages
Check and clean the engine cool-
ing water passages.
Damaged or leaking radiator Replace the radiator.
Faulty radiator cap Replace the radiator cap.
Clogged radiator fin Clean the radiator fin.
Bent or damaged radiator fin
Repair the radiator fin or replace
the radiator.
Damaged or faulty water pump Replace the water pump.
Damaged hoses or pipes Replace the hose or pipe.
Improperly connected hoses or
pipes
Connect the hoses and pipes
properly.
Clogged air filter element
Clean or replace the air filter ele-
ment.
Brake drags
Check the brake system and
repair or replace faulty parts as
necessary.
Incorrect spark plug gap
Adjust to the specified spark plug
gap.
Incorrect spark plug heat range
Replace the spark plug with the
one of the specified type.
Noise from water pump
Contact between the water pump
housing cover and impeller
Disassemble the water pump and
replace faulty parts.
Worn water pump housing bearing
Replace the water pump housing
bearing.

Yamaha YZ250 2021 Specifications

General

Engine Type	249cc liquid-cooled 2-stroke; reed-valve inducted
Bore x Stroke	66.4mm x 72.0mm
Compression Ratio	8.9~10.6:1
Ignition	CDI
Transmission	5-speed; multiplate wet clutch
Final Drive	Chain
Suspension Rear	KYB® single shock; fully adjustable, 12.4-in travel
Brakes Front	Hydraulic disc, 270mm
Tires Front	80/100-21
Tires Rear	110/90-19
Width	32.5 in
Height	50.8 in
Wheelbase	58.5 in
Ground Clearance	14.2 in
Fuel Capacity	2.1 gal
Wet Weight	227 lb
Fuel Delivery	Keihin PWK38S carburetor
Suspension Front	KYB® Speed-Sensitive System inverted fork; fully adjustable, 11.8-in travel
Brakes Rear	Hydraulic disc, 245mm