Yamaha YZ250FM 2021 Owner's Service Manual

CAMSHAFT5-19a. Turn the crankshaft counterclockwise witha wrench.TIP• Apply molybdenum disulfide oil to the cam-shafts.• Apply the engine oil on the decompressionsystem.• Fill the cylinder head with engine oil up to thetops “a” of the valve lifters.b. Align the top dead center (TDC) mark “a”on the generator rotor with the alignmentmark “b” on the crankcase cover.c. Fit the timing chain “3” onto both camshaftsprockets and install the camshafts on thecylinder head.TIPMake sure that the alignment mark “c” on the ex-haust camshaft sprocket and the alignmentmark “d” on the intake camshaft sprocket arealigned with the edge of the cylinder head.NOTICEECA24620Do not turn the crankshaft during the cam-shaft installation. Damage or improper valvetiming will result.d. Install the clips, the camshaft caps and thebolts (camshaft cap).TIP• Before installing the clips, cover the cylinderhead with a clean cloth to prevent the clipsfrom coming off into the cylinder head cavity.• Apply the engine oil to the threads and contactsurfaces.• Tighten the bolts to the specified torque in twoor three steps in the proper tightening se-quence as shown.NOTICEECA24630The bolts (camshaft cap) must be tightenedevenly, or damage to the cylinder head, cam-shaft caps, and camshaft will result.2. Install:• Timing chain tensionera. While pressing the tensioner rod lightlywith your fingers, use a thin screwdriver towind the tensioner rod up fully clockwise.22 11MEa a abaBolt (camshaft cap)10 N·m (1.0 kgf·m, 7.4 lb·ft)d c3T R..111 2233 4466 5588 77E