Ruggerini RY 50 - Clearance; Piston - Refitting; Piston Rings, Assembly Order; Piston Rings, Play between the Slots (MM)

34
17-04-2003
01
15-01-2004
DATE
COMPILER TECO/ATI
REG. CODE
1-5302-584
MODEL N°
50871
DATE OF ISSUE
REVISION
ENDORSED
43 44
VIII
45
46
47
05YR07YR301-57YR011YR
A
511.0÷70.001.0÷70.011.0÷530.011,0÷70,0
B
80.0÷40.080.0÷50.090.0÷050.090,0÷50,0
C
70.0÷30.0570.0÷40.0780.0÷030.070,0÷30,0
DISASSEMBLY/REASSEMBLY
Piston rings, play between the slots (mm)
Replace the piston or piston rings if the value exceeds the
maximum limit.
Piston rings, assembly order
A = 1st Chromium plated piston ring (nitrided for RY 50-75-103)
B = 2nd piston ring (torsional)
C = 3rd piston ring (oil scraper) (nitrided for RY 50-75-103)
D = Chromium plated zone
Note: If a word (top, or some other word) is written on the surface of
a piston ring, mount that surface upwards.
Before inserting the piston into the cylinder, oil and turn the
piston rings so that the cuts are staggered 120° to each
other.
In RY 75 and RY 50 engines, the second piston ring is not
torsional, while the first and third piston rings do not have
chromium plated zones but are nitrided.
Lubricate the following parts with oil before mounting: the
piston pin, the piston, the cylinder and the big-end bearing
Piston - Refitting
Connect piston to connecting rod, lubricate piston pin and introduce
it into the piston/connecting rod assembly by exerting pressure with
your thumb.
Fit both piston pin circlips and check that they are well seated.
When introducing both the connecting rod and the piston into the
cylinder make sure that the larger crown surface A (if compared to
the combustion chamber) is on the same side as the pushrod
opening B.
Clearance
A = Clearance
C = Head gasket
The thickness of gasket C determines the clearance A, which must
be 0.45-0.55 mm for RY 70 with injection pump serial N° 6590-259;
it is 0.50-0.60 mm with injection pump serial N° 6590-281.
The clearance is 0.45-0.55 mm for RY 50 in all cases.
The clearance is 0.50-0.60 mm for RY 75-103-110 in all cases.
For the correct thickness of gasket C see table in fig. 49÷50.
There are gaskets with inner diameters oversized by 1 mm for RY
70-75, required if the cylinders are ground.