Generac 86640 - Manual (Page 43)

8. Surface warpage must be less than 0.004 inch (0.1mm). If
beyond the specified limit, resurface the cylinder block. Re­
surfacing limit of the cylinder block is determined by the
amount of resurfacing done on the cylinder head. If the
amount of resurfacing on the cylinder head is “A" and the
resurfacing on the cylinder block is "B‘, the maximum limit is
as
I
A + B = 0.008 inch (0.2mm)
I
CAUTION: When resurfacing, use care not to cut
off the punched piston grade number.________________
9. Use a bore gauge to measure the cylinder bore for wear,
taper or out-of-round. Inspect for scratches or seizure. Hone
the bore as necessary.
STANDARD INSIDE DIAMETER
2.7953-2.7965 inch (71.00-71.03mm)
OUT-OF-ROUND (X-Y) LIMIT
0.0008 inch (0.02mm)
TAPER (A-B) LIMIT
0.0008 inch (0.02mm)
10. Use a micrometer to measure the piston skirt diameter
(Figure 61). The measuring point for checking piston skirt
diameter is 0.35 inch (9mm) as shown in Figure 63 (Point “L").
STANDARD PISTON SKIRT DIAMETER
2.6759-2.6770 inch (67.967-67.997mm)
tions.
Piston clearance must be within the stated specifica-
PiSTON CLEARANCE
0.0009-0.0017 inch (0.023-0.043 mm)
11. To measure piston clearance, use a 0.0016 inch
(0.04mm) feeler gauge, inserted between the piston and the
cylinder bore (Figure 64). The force required to remove the
feeler gauge should be as follows:
REMOVAL FORCE
1.1-3.3 pounds (0.5-1.5kg)
12. Check flywheel runout (Figure 65). Total indicator reading
(T.I.R.) should be less than the value specified below.
T.I.R. RUNOUT
Less than 0.0059 inch (0.15mm)
Page 2.6-3