VESPA 633844 IT Service Manual page 146

Engine
N.B.
THE MAIN BEARINGS ARE NOT GRINDABLE
Specific tooling
020074Y Support base for checking crankshaft
alignment
Characteristic
Off-line maximum admitted
A = 0.15 mm
B = 0.01 mm
C = 0.01 mm
D = 0.10 mm
Inspecting the crankcase halves
- Before proceeding to check the crankcase
halves, thoroughly clean the all surfaces and oil
ducts.
- On the transmission-side crankcase half, take
particular care when handling the oil pump com-
partment and the oil ducts, the by-pass duct, the
main bushings and the cooling jet on the trans-
mission side (see diagram).
- Take particular care, also, that there are no signs
wear in the oil by-pass valve housing (see Chapter
Lubrication), as this could prevent a good seal in
the valve, which regulates the oil pressure.
- On the flywheel side crankcase half, take partic-
ular care cleaning the oil ducts for the main bush-
ings, the oil duct for the jet that lubricates the
cylinder head and the oil drainage duct at the fly-
wheel side oil seal.
- Inspect the coupling surfaces on the crankcase
halves for scratches or deformation, taking partic-
ular care with the cylinder/crankcase surfaces and
the crankcase halves surfaces.
- Defects in the crankcase coupling gasket be-
tween the crankcase halves or the mating surfaces
shown in the diagram, could cause a drop in the
oil pressure lubricating the main bearings and con-
nection rod.
ENG - 52
Vespa GTV 250 i.e.