Piston Diameter Measurement
Measure the outside diameter [A] of each piston 5 mm
(0.20 in.) [B] up from the bottom of the piston at a right
angle to the direction of the piston pin.
If the measurement is under the service limit, replace the
73.942 ∼ 73.957 mm (2.911 ∼ 2.912 in.)
73.79 mm (2.91 in.)
When boring and honing a cylinder, note the following:
There is one oversize piston available. Oversize pistons
require oversize rings. Oversize pistons and rings avail-
able are 0.5 mm (0.020 in.) larger than standard.
Before boring a cylinder, first measure the exact diameter
of the oversize piston, and then, according to the standard
clearance in the Service Data Section, determine the re-
bore diameter. However, if the amount of boring neces-
sary would make the inside diameter greater than 0.5 mm
(0.020 in.) oversize, the cylinder block must be replaced.
Cylinder inside diameter must not vary more than 0.01
mm (0.0004 in.) at any point.
Be wary of measurements taken immediately after boring
since the heat affects cylinder diameter.
In the case of a rebored cylinder and oversize piston, the
service limit for the cylinder is the diameter that the cylin-
der was bored to plus 0.1 mm (0.0039 in.) and the service
limit for the piston is the oversize piston original diameter
minus 0.15 mm (0.0059 in.) If the exact figure for the re-
bored diameter is unknown, it can be roughly determined
by measuring the diameter at the base of the cylinder.
Never separate the liner from the cylinder, because the
top surface of cylinder and liner is machined at the factory
as an assembly.
ENGINE TOP END 4-33