INSPECTION AND REPAIR OF BASIC ENGINE
6-21
4.15 Measuring crankcase top surface distor-
tion
&$87,21
Refacing of cylinder head should be kept to an abso-
lute minimum.
Excessive grinding of the cylinder head may result in
defects such as defective combustion and stamping
(contact between piston and valve).
Apply a straight edge to the top surface of the crankcase and
measure its distortion using a feeler gauge. If the distortion
exceeds the limit, grind the cylinder head using a surface
grinder.
Note: Do not overgrind the cylinder head, as the piston
protrusion deviates from the standard value.
Note: Do not grind the surfaces more than 0.2 mm
[0.008 in.] in total (cylinder head bottom surface plus
crankcase top surface).
Measuring crankcase top surface distortion
4.16 Inspecting tappet
Inspect the cam contact surface of the tappets. Fit new
tappets if the surface is excessively worn or damaged.
Contact surface of tappet and cam
4.17 Measuring clearance between tappet and
tappet guide hole
Measure clearance between the tappet and tappet hole.
Replace the tappet with a new one if the limit is exceeded.
Measuring tappet outside diameter and crankcase
tappet bore inside diameter
Item
Standard
Limit
Distortion of crankcase
top surface
0.05 mm
[0.0020 in.] or less
0.20 mm
[0.0079 in.]
Good
Bad
Bad
Item
Nominal
Standard
Limit
Tappet hole
inside diameter
ø 14 mm
[0.55 in.]
14.000 to 14.018 mm
[0.5512 to 0.5519 in.]
14.100 mm
[0.5551 in.]
Clearance
between tappet
and tappet hole
-
0.016 to 0.052 mm
[0.0006 to 0.0020 in.]
0.080 mm
[0.0031 in.]
Measuring
direction
Measuring
direction
Measuring
points
Measuring
points
