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10
Checks and overhaul
20
21
22
23
- 22 -
The operation is carried out by applying a calibrated pressure to
the convex side in the middle of the connecting rod stem set on
surface plates (fig. 20).
Crankshaft
It is advisable to check the condition of the crankshaft whenever
the engine is demounted and particularly when cylinders and
pistons must be replaced following wear due to dust having
been intaken.
Thoroughly clean inside the oil ducts using a shaped metal point.
If there are heavily caked incrustations, immerse the crankshaft
into a bath of petroleum or gasoline before proceeding with the
scraping operation (fig. 21).
When the crankshaft is perfectly clean, check with a micrometer
to ascertain wear and main journal ovality in the two
perpendicular positions (fig. 22).
Grind the shaft if the wear exceeds the values in the table by
0.08 mm or more.
Dimensions
A C
B
NOTE: crankshaft grinding operations of more than 0.25
mm should not be carried out.
Undersized bearings can be mounted without any reaming work
required.
WARNING: do not remove material from the main journal
shims during the grinding operation as this would
alter crankshaft float. Also make sure that the grinder
radii correspond to those indicated in fig. 21 to prevent
fracture sections from initiating on the shaft.
Oil retention rings
Make sure that the rings have not hardened in the retention lip
and that there is no sign of breakage or wear.
Lubrication circuit
Lubrication of the main bearings and connecting rod big end is
the forced type with a rotor oil pump.
Excessive pressure in the oil circuit is prevented by the by-pass
valve (3, fig. 23).
All the other parts are splash lubricated.
Oil vapours are eliminated from inside the casing by a
diaphragm mounted in the rocker arm cover.
Illustration in fig. 23:
1. Internal intake oil filter in casing - 2. Oil pump - 3. By-pass
valve - 4. Engine oil filter - 5. Pressure switch - 6. Main bearing -
7. Big end bearing.
Workshop Manual KD500 _ cod. ED0053029390 - 1° ed_rev. 00
STD mm
-0,25 mm
41,97 ÷ 41,99
41,72 ÷ 41,74
39,98 ÷ 40
39,73 ÷ 39,75
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