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.
- Check the main bearing seats that limit axial
clearance in the crankshaft show no signs of wear.
The dimension between these seats is measured
by way of the procedure described previously for
measuring the crankshaft axial clearance and di-
mensions.
N.B.
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 LEAKS CAN CAUSE A CONSID-
ERABLE DROP IN THE LUBRICATION PRESSURE FOR
MAIN BUSHINGS AND CONNECTING ROD .
N.B.
THE HEAD LUBRICATION CHANNEL IS PROVIDED WITH
A SHUTTER JET; THIS GIVES A "LOW PRESSURE" HEAD
LUBRICATION; THIS CHOICE WAS MADE TO REDUCE
THE OIL TEMPERATURE IN THE SUMP. THE JET CLOG-
GING IMPAIRS THE HEAD LUBRICATION AND THE TIM-
ING MECHANISMS. A JET FAILURE CAUSES A DE-
CREASE OF THE MAIN BUSHING AND CONNECTING ROD
LUBRICATION PRESSURE.
Inspecting the crankshaft plain bearings
Refitting the crankcase halves
- Fit the internal bulkhead by locking the two
screws to the prescribed torque.
- Fit the oil filter fitting and tighten it to the specified
torque.
- Place a new gasket on one of the crankcase
halves, preferably on the transmission side, to-
gether with the locating dowels.
- Lubricate the main bushings and insert the crank-
shaft in the transmission side crankcase half.
- Reassemble the two crankcase halves.
Engine X9 Evolution 125
ENG - 140
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