VESPA GTS Super 300 ie 2008 Service Station Manual page 23

Vespa GTS Super 300 ie (2008)
Characteristic
Crankshaft-crankcase axial clearance (H)
0.15 ÷ 0.43 mm
- Using a bore gauge, measure the connecting rod
small end diameter.
N.B.
IF THE CONNECTING ROD SMALL END DIAMETER EX-
CEEDS THE STANDARD DIAMETER, EXHIBITS WEAR OR
OVERHEATING, PROCEED TO REPLACE THE CRANK-
SHAFT AS DESCRIBED IN THE CRANKCASE AND
CRANKSHAFT CHAPTER.
Characteristic
Standard diameter
16 +0.025 +0.015 mm
- To obtain a good bushing lubrication it is necessary to have both an optimal lubricating pressure and
a good oil flow rate; the bushings must be correctly positioned so as not to obstruct the oil supply
channels.
- The main bushings are comprised of two half-bearings, one with holes and channels for lubrication
whereas the other is solid.
- 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 shutters in the oil feeding channels, the matching surface of the two half-bearings must be
perfectly orthogonal to the cylinder axis, 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 BLUE bushings, with YELLOW bushings and with GREEN
bushings.
- There is only one type of main bushing housing hole in the crankcase. The standard bushing diameter
after driving is variable on the basis of a coupling selection.
- The bushing housings in the crankcase are classified into 2 categories - Cat. 1 and Cat. 2 - just like
those for the crankshaft.
- The main bushings are available in three thickness categories, identified by colour markings, as shown
in the table below.
TYPE
B
C
E
BUSHINGS
IDENTIFICATION
BLUE
YELLOW
GREEN
Characteristics
CRANKSHAFT HALF-BEARING
1.973 to 1.976
1.976 to 1.979
1.979 to 1.982
CHAR - 23