APRILIA SCARABEO 500 2008 Service Station Manual page 207

SCARABEO 500
NOTE
THE JET IS FED THROUGH THE MAIN BUSH-
INGS. PROPER OPERATION OF THIS COMPO-
NENT IMPROVES PISTON CROWN COOLING.
CLOGGING HAS EFFECTS THAT ARE DIFFI-
CULT TO DETECT (PISTON TEMPERATURE
INCREASE). FAILURE OR LEAKAGE CAN
CONSIDERABLY CAUSE A DROP IN LUBRI-
CATION PRESSURE FOR THE MAIN BUSH-
INGS AND CONNECTING ROD.
- For the flywheel-side crankcase half, special at-
tention should be given to the lubrication channels
for the main bushings and to the compartment and
channels for the oil pump, as well as to the duct for
the by-pass located on the flywheel cover.
NOTE
AS ALREADY DESCRIBED IN THE LUBRICA-
TION CHAPTER, IT IS ESPECIALLY IMPOR-
TANT THAT THE BY-PASS VALVE HOUSING
SHOWS NO WEAR THAT MAY IMPAIR THE
PROPER SEALING OF THE LUBRICATION
PRESSURE ADJUSTMENT PISTON. THE
HEAD LUBRICATION CHANNEL IS FITTED
WITH A SHUTTER JET; THIS GIVES A "LOW
PRESSURE" HEAD LUBRICATION. THIS
CHOICE HAS BEEN MADE TO REDUCE THE
OIL TEMPERATURE IN THE SUMP.
Jet clogging impairs head lubrication and the timing mechanisms.
A jet failure causes a drop in lubrication pressure for the main bushings and connecting rod.
- Check the coupling surfaces for scratches or deformation, paying special attention to the cylinder -
crankcase surfaces and the crankcase halves coupling surfaces.
- Defects in the crankcase coupling gasket or the surfaces can cause a drop in the oil pressure and
affect the lubricating pressure.
- Check that the surfaces limiting the crankshaft axial clearance show no signs of wear. To measure
and check sizes follow the procedure described previously for checking crankshaft axial clearance and
dimensions
Engine
ENG - 207