Derbi Rambla 250, Руководство пользователя, Страница: 129 / 259

Inspecting the crankcase halves
- Before checking the crankcase halves, thorough-
ly clean all the surfaces and oil pipes.
- For the crankcase half on the transmission side,
take particular care cleaning the housing and oil
pipes of the oil pump, the duct and the by-pass
valve, the main bushings and the cooling nozzle
on the transmission side (see figure).
As already described in the lubrication chapter, it
is especially important that the by-pass valve
housing shows no wear that may impair the proper
sealing of the lubrication pressure adjustment pis-
ton.
- For 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.
- Check the coupling surfaces for scratches or de-
formation, paying special attention to the cylinder
- crankcase surfaces and the crankcase halves
coupling surfaces.
- Defects in the crankcase coupling gasket or the
surfaces indicated in the figure can cause a drop
in oil pressure and thus affect the lubricating pres-
sure for the main bushings and the connecting rod.
- Check that the surfaces limiting the crankshaft
axial clearance show no signs of wear. To meas-
ure and check sizes follow the procedure descri-
bed previously for checking crankshaft axial
clearance and dimensions.
NOTE
THE JET IS FED THROUGH THE MAIN BUSHINGS. PROP-
ER OPERATION OF THIS COMPONENT IMPROVES PIS-
TON CROWN COOLING. CLOGGING HAS EFFECTS THAT
ARE DIFFICULT TO DETECT (PISTON TEMPERATURE IN-
CREASE). FAILURE OR LEAKAGE CAN CONSIDERABLY
CAUSE A DROP IN LUBRICATION PRESSURE FOR THE
MAIN BUSHINGS AND CONNECTING ROD.
NOTE
THE HEAD LUBRICATION CHANNEL IS PROVIDED WITH
A SHUTTER JET: THIS GIVES A "LOW PRESSURE" HEAD
LUBRICATION; THIS CHOICE HAS BEEN MADE TO RE-
Engine
ENG - 129