Service Manual

5-22 ENGINE TOP END
Cylinder, Piston
Piston Diameter
•
Measure the outside diameter [A] of the piston 11 mm
(0.43 in.) [B] up from the bottom of the piston at a right
angle to the direction of the piston pin hole.
If the measurement is less than the service limit, replace
the piston with a new one.
Piston Diameter
Service Limit: 77.79 mm (3.063 in.)
Cylinder Inside Diameter
•
Clean and measure the cylinder inside diameter.
○
Use a cylinder gauge to measure front-to-back and side
-to-side at the points as shown in the figure.
If any of the cylinder inside diameter measured value is
greater than the service limit, replace the crankcase with
a new one.
10 mm (0.39 in.) [A]
40 mm (1.6 in.) [B]
25 mm (0.98 in.) [C]
Cylinder Inside Diameter
Standard:
Standard Cylinder
77.98 ∼ 78.00 mm
(3.070 ∼ 3.071 in.)
0.50 mm Oversize
78.48 ∼ 78.50 mm
(3.090 ∼ 3.091 in.)
Service Limit:
Standard Cylinder 78.08 mm (3.074 in.)
0.50 mm Oversize 78.58 mm (3.094 in.)
Cylinder Bore Out Round
Service Limit: 0.05 mm (0.002 in.)
Cylinder Boring and Honing
Always resize to exactly 0.5 mm (0.02 in.) over the stan-
dard bore size. If this is done accurately, the stock oversize
rings and piston will fit perfectly and proper clearance will
be maintained. Resizing the cylinder bore can be done by
reliable repair shop or by using a drill press and honing tool.
Use the stone recommended by the hone manufacturer to
produce correct cylinder wall finish. Machine-bore first, the
bore diameters should be shown in the table.
Final Boring Bore Diameter
Oversize Final Boring Bore Diameter
0.50 mm 78.46 ∼ 78.48 mm (3.089 ∼ 3.090 in.)
Final Bore Diameter
Oversize Final Bore Diameter
0.50 mm 78.48 ∼ 78.50 mm (3.090 ∼ 3.091 in.)