ENGINE
B2301, B2601, WSM
[4] SERVICING (1) Cylinder Head and Valves Top Clearance 1. Remove the cylinder head. (Do not try to remove the cylinder head gasket.) 2. Move the piston up and stick a strip of fuse [1.5 mm dia. (0.059 in. dia.), 5.0 to 7.0 mm long (0.20 to 0.27 in. long)] on the piston head at three positions with grease so as to avoid the intake valve and the exhaust valve and the combustion chamber ports. 3. Lower the piston, and install the cylinder head and tighten the cylinder head screws to the specified torque. 4. Turn the flywheel until the piston exceeds top dead center. 5. Remove the cylinder head, and measure the thickness of the squeezed fuses. 6. If the measurement is not within the factory specifications, check the oil clearance between the crankpin and the crankpin bearing and between the piston pin and the small end bushing. NOTE • After checking the top clearance, be sure to assemble the cylinder head with a new cylinder head gasket. Top clearance
Tightening torque (1) Fuse
Factory specification
Cylinder head screws
0.55 to 0.75 mm 0.022 to 0.029 in. 64 to 68 N·m 6.5 to 7.0 kgf·m 47 to 50 lbf·ft
(2) Fuse 9Y1211156ENS0054US0
Cylinder Head Surface Flatness 1. Clean the cylinder head surface. 2. Place a straightedge on the cylinder head's four sides and two diagonal as shown in the figure. 3. Measure the clearance with a thickness gauge. 4. If the measurement exceeds the allowable limit, correct it with a surface grinder. IMPORTANT • Do not place the straightedge on the combustion chamber. • Be sure to check the valve recessing after correcting. Cylinder head surface flatness
Allowable limit
0.05 mm 0.002 in. 9Y1211156ENS0055US0
1-S37
KiSC issued 11, 2014 A
