- The solid half-bearing is intended to stand the
thrusts caused by combustion, and for this reason
it is arranged opposite the cylinder.
- To prevent obstructions in the oil feeding chan-
nels, the matching surface of the two half-bearings
must be perfectly perpendicular to the cylinder ax-
is, as shown in the figure.
- The oil feeding channel section is also affected
by the bushings driving depth compared with the
crankshaft axial clearance of the limiting surface.
- Check the inside diameter of the main bushings
in the three directions indicated in the diagram.
- Repeat the measurements for the other bushing
half. see diagram.
- There are three crankcase versions: with RED
main bushings, with BLUE main bushings and with
YELLOW main bushings.
- There is only one type of main bushing housing
hole in the crankcase
The standard bushing diameter after driving is var-
iable on the basis of a coupling selection.
- The bushing housings in the crankcase are avail-
able in two categories, Cat. 1 and Cat. 2, as are
the crankshafts.
- The main bushings are available in three thick-
ness categories, identified by colour markings, as
shown in the table below.
TYPE IDENTIFICATION
A RED
B BLUE
C YELLOW
Type "A"
- RED
Type "B"
- BLUE
Type "C"
- YEL-
LOW
Crankshaft
half-bearing
1.970 ÷
1.973
1.9703 ÷
1.976
1.976 ÷
1.979
Engine Runner 125 - 200
ENG - 178
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