Servicing; Cylinder Head And Valves - wsm STW37 Workshop Manual

STW34, STW37, STW40, WSM

[4] SERVICING

(1) Cylinder Head and Valves

Top Clearance
1. Remove the cylinder head.
2. With the piston at TDC, use grease to affix three or four
plastigauges (1) of a diameter 1.5 mm (0.059 in.) × 5.0 to
7.0 mm (0.20 to 0.27 in.) long to the crown of the piston; keep
the gauges away from the intake valve and combustion
chamber fittings.
3. Take the piston to an intermediate position, install the cylinder
head and tighten the head screws to the specified torque.
4. Turn the crankshaft so the piston goes through TDC.
5. Remove the cylinder head and compare the width of the
crushed plastigauges (2) with the scale (3).
6. If they are out of spec, check the oil clearance of the crank pin,
journals and piston pin.
IMPORTANT
• Top clearance = Width of the crushed plastigauge (2).
Top clearance Factory specification
Tightening torque Cylinder head screw
(1) Plastigauge
(2) Crushed Plastigauge
Cylinder Head Flaw
1. Prepare an air spray red check (Code No. 07909-31371).
2. Clean the surface of the cylinder head with the detergent (2).
3. Spray the cylinder head surface with the red permeative liquid
(1). Leave it five to ten minutes after spraying.
4. Wash away the red permeative liquid on the cylinder head
surface with the detergent (2).
5. Spray the cylinder head surface with the white developer (3).
6. If flawed, it can be identified as red marks.
(1) Red Permeative Liquid
(2) Detergent
1-S63
ENGINE
0.55 to 0.70 mm
0.022 to 0.027 in.
93.2 to 98.0 N·m
9.50 to 10.0 kgf·m
68.8 to 72.3 lbf·ft
(3) Scale
9Y1211109ENS0092US0
(3) White Developer
9Y1211109ENS0093US0
KiSC issued 11, 2014 A