Yamaha YZ250 2021 User Manual

CHAIN DRIVE
4-30
c. Remove the drive chain from the kerosene
and completely dry it.
4. Check:
• Drive chain roller “1”
Damage/wear  Replace the drive chain.
• Drive chain side plate “2”
Damage/wear  Replace the drive chain.
5. Lubricate:
• Drive chain
EAM30560
CHECKING THE DRIVE CHAIN (for YZ250X)
1. Measure:
• 15-link section of the drive chain
Out of specification  Replace the drive
chain.
a. Measure the length “a” between the inner
sides of the pins and the length “b” be-
tween the outer sides of the pins on a 15-
link section of the drive chain as shown in
the illustration.
b. Calculate the length “c” of the 15-link sec-
tion of the drive chain using the following
formula.
Drive chain 15-link section length “c” =
(length “a” between pin inner sides +
length “b” between pin outer sides)/2
TIP
• When measuring a 15-link section of the drive
chain, make sure that the drive chain is taut.
• Perform this procedure 2–3 times, at a different
location each time.
2. Check:
• Drive chain
Stiffness  Clean, lubricate, or replace.
3. Clean:
• Drive chain
a. Wipe the drive chain with a clean cloth.
b. Put the drive chain in kerosene and re-
move any remaining dirt.
c. Remove the drive chain from the kerosene
and completely dry it.
15-link length limit
239.3 mm (9.42 in) (YZ250X)
G088940
2
1
G088942
G088937
G088938
G088939

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