Yamaha WR250FM service manual Valve Clearance Inspection and Adjustment

VALVE CLEARANCE INSPECTION AND ADJUSTMENT

INSP

ADJ

3.Remove:

•Right radiator

Refer to “RADIATOR” section in the CHAPTER 4.

•Carburetor

Refer to “CARBURETOR” section in the CHAPTER 4.

•Spark plug

•Upper engine bracket

•Cylinder head cover

Refer to “CAMSHAFTS” section in the CHAPTER 4.

4.Remove:

•Timing mark accessing screw 1

•Crankshaft end accessing screw 2

•O-ring

5.Check:

•Valve clearance

Out of specification → Adjust.

Valve clearance (cold):

Intake valve:

0.10~ 0.15 mm (0.0039 ~ 0.0059 in)

Exhaust valve:

0.17~ 0.22 mm (0.0067 ~ 0.0087 in)

Checking steps:

•Turn the crankshaft counterclockwise with a wrench.

•Align the T.D.C. mark a on the rotor with the align mark b on the crankcase cover when piston is at T.D.C. on compression stroke.

NOTE:

In order to be sure that the piston is at Top Dead Center, the punch mark c on the exhaust camshaft and the punch mark d on the intake camshaft must align with the cyl- inder head surface, as shown in the illustra- tion.

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