APRILIA Atlantic 300 Service Station Manual page 24

Characteristics
Characteristic
Crankshaft-crankcase axial clearance (H)
0.15 ÷ 0.40 mm
- Measure the inside diameter of the connecting
rod small end using a bore meter.
NOTE
IF THE CONNECTING ROD SMALL END DIAMETER EX-
CEEDS THE STANDARD DIAMETER, SHOWS SIGNS OF
WEAR OR OVERHEATING, REPLACE THE CRANKSHAFT
AS DESCRIBED IN THE «CRANKCASE AND CRANK-
SHAFT» CHAPTER.
Characteristic
Standard diameter
16 +0.025 +0.015 mm
- In order to obtain proper bushing lubrication, make sure there are both an outstanding lubrication
pressure and a good oil flow rate. To that end, the bushings must be correctly positioned so as not to
obstruct the oil supply channels.
- The main bushings are comprised of 2 half-bearings, one with holes and channels for lubrication while
the other is solid.
- The solid half-bearing is intended to stand the thrusts caused by combustion, and for this reason, it is
arranged opposed to the cylinder.
- So as not to obstruct the oil supply channels, the coupling surface of the two half-bearings must be
perpendicular to the cylinder axis as shown in the figure.
- The oil supplying channel section is also influenced by the depth to which the bushings are driven
compared with the crankshaft axial clearance of the limiting surface.
- Measure the bushings diameter at the 3 positions indicated in the figure.
- Repeat the measurements for the other half of the bushing. See figure.
- There are three crankcase versions: with BLUE, YELLOW or GREEN bushings.
- There is just one type of bushing housing in the crankcase. The standard diameter of the bushings
after fitting depends on the choice of coupling.
- There are 2 categories of bushing seats in the crankcase - Cat 1 and Cat 2 - just like those for the
crankshaft
- The main bushings are subdivided into 3 categories according to thickness; see table below:
TYPE
B
C
E
BUSHING CATEGORY
HALVES CATEGORY
B
CHAR - 24
BUSHINGS
IDENTIFICATION
BLUE
YELLOW
GREEN
COMBINATIONS
CRANKCASE
2
ATLANTIC 300 i.e.
CRANKSHAFT HALF-BEARINGS
BUSHING INSIDE DIAMETER AFTER FITTING
29.024 ÷ 29.054
1.973 ÷ 1.976
1.976 ÷ 1.979
1.979 ÷ 1.982