Toro Workman 3000 Series Service Manual page 148

3. Use a cylinder gauge to measure inside diameter of
cylinder in six (6) locations as shown. Calculate differ­
ence between maximum and minimum values (cylin­
dricity). If there is excessive wear or damage, rebore or
replace cylinder block.
Standard value
Cylindricity
Cylinder diameter
Limit
Cylindricity
4. Calculate difference between minimum inside diame­
ter in the thrust direction and outside diameter of piston
at place shown in illustration. If difference is outside the
standard value re–bore the cylinders and use oversize
pistons and rings.
Standard value 0.02 – 0.04 mm (.0008 – .0016 in.)
Cylinder Re–boring
1. Use cylinder with maximum inside diameter and most
extensive damage as a base and select an over–size
(O.S.) piston.
2. Calculate cylinder boring dimension from outside di-
ameter (at correct measuring location) of O.S. piston se­
lected.
Boring dimension = (piston outside diameter) +
(piston clearance) – (honing value: 0.02 mm [.0008 in.])
O.S. piston outside diameters
and cylinder inside diameters (reference)
Size Mark Outside diameter
of piston
0.25 O.S. 25 65.22 – 65.25
(2.5677 – 2.5689)
0.50 O.S. 50 65.47 – 65.50
(2.5776 – 2.5787)
0.75 O.S. 75 65.72 – 65.75
(2.5874 – 2.5886)
1.00 O.S. 100 65.97 – 66.00
(2.5972 – 2.5984)
3. Bore cylinder until diameter is at value calculated.
4. Hone cylinder to cylinder boring dimension.
5. Check cylindricity and piston clearance again.
Liquid Cooled Gas Engine
0.01 mm (.0004 in.) or less
65.00 – 65.03 mm
(2.5591 – 2.5602 in.)
.02 mm (.0008 in.)
mm (in.)
Inside diameter
of cylinder
65.26 – 65.27
(2.5693 – 2.5697)
65.51 – 65.52
(2.5791 – 2.5795)
65.76 – 65.77
(2.5890 – 2.5894)
66.01 – 66.02
(2.5988 – 2.5992)
Page 3 – 110
Figure 241
40 mm
(1.57 in.)
Figure 242
Workman 3000/4000 Series
12 mm (.47 in.)
12 mm (.47 in.)