Operation Manual

- Remove the two screws and the internal cover
shown in the diagram.
- Remove the oil guard on the flywheel side.
- Remove the oil filter fitting shown in the diagram.
- Check the axial clearance on the connecting rod.
- Check the radial clearance on the connecting rod.
-Check the surfaces that limit the axial free-play
are not scored and measure the width of the crank-
shaft between these surfaces, as shown in the
diagram.
- If the axial clearance between crankshaft and
crankcase is exceeding and the crankshaft does
not have any defect, the problem must be due to
either excessive wear or wrong machining on the
crankcase.
- Check the diameters of both the bearings of the
crankshaft in accordance with the axes and surfa-
ces shown in the figure. The half-shafts are clas-
sified in two categories Cat. 1 and Cat. 2 as shown
the chart below.
CAUTION
THE CRANKSHAFT CAN BE REUSED WHEN
THE WIDTH IS WITHIN THE STANDARD VAL-
UES AND THE SURFACES SHOW NO SIGNS
OF SCORING.
CAUTION
WHILE OPENING THE CRANKCASES AND RE-
MOVING THE DRIVING SHAFT, CHECK THAT
THE THREADED SHAFT ENDS DO NOT INTER-
FERE WITH THE MAIN BUSHINGS. FAILURE
TO OBSERVE THIS PRECAUTION CAN DAM-
AGE THE MAIN BUSHINGS.
CAUTION
KEEP THE CRANKSHAFT IN ONE OF THE TWO
HALVES OF THE CRANKCASE WHEN SEPA-
RATING IT. IF YOU FAIL TO DO THIS, THE
CRANKSHAFT MIGHT ACCIDENTALLY FALL.
N.B.
WHEN MEASURING THE WIDTH OF THE
CRANKSHAFT, MAKE SURE THAT THE MEAS-
UREMENTS ARE NOT MODIFIED BY THE RAD-
IUSES OF FITTINGS WITH THE CRANKSHAFT
BEARINGS.
Specific tooling
Engine MP3 250 i.e.
ENG - 50