Service Manual

ENGINE TOP END 5-13
Cylinder Head
Cylinder Head Inspection
•
Lay a straightedge [A] across the mating surface of the
head at several different points, and measure warp by
inserting a thickness gauge [B] between the straightedge
and head.
If warp exceeds the service limit, repair the head by lap-
ping the mating surface with emery paper secured to a
surface plate (first No. 200, than No. 400). If the mating
surface is badly damaged, replace the cylinder head.
Cylinder Head Warp
Service Limit: 0.05 mm (0.002 in.)
•
Check the cylinder head for cracks or other damage.
•
Cracks not visible to the eye may be detected by coating
the suspected area with mixture of 25% kerosene and
75% light engine oil.
•
Wipe the area dry and immediately apply a coating of zinc
oxide dissolved in wood alcohol. If a cracks is present, the
coating will become discolored at the defective area.
•
If a cracks is present in the cylinder head, replace it.
•
Inspect the mating surface for burrs and nicks.
Rocker Arm Inspection
•
Measure the diameter [A] of the rocker shafts with a mi-
crometer at several points of bearing the rocker arm.
If the outside diameter is less than the service limit, re-
place the rocker shaft.
Rocker Shafts Outside Diameter
Service Limit:
Inlet, Exhaust 10.91 mm (0.430 in.)
•
Clean and inspect the rocker arm where it touches the
push rod and valve stem.
If the contact points [A] are worn or damaged, replace the
rocker arm.
•
Measure the inside diameter [B] of the rocker arm at sev-
eral points using a dial bore gauge or inside micrometer.
If the inside diameter is more than the service limit, re-
place the rocker arm.
Rocker Arm Inside Diameter
Service Limit:
Inlet, Exhaust 11.13 mm (0.438 in.)