Piston Rings; Crankcase - Crankshaft - Connecting Rod; Categories Of Coupling; Sealing Rings - Gilera Nexus 500 Workshop Manual

Characteristics
Specification
Name
Cylinder Piston
Cylinder Piston
Cylinder Piston
Cylinder Piston
N.B.
THE PISTON MUST BE INSTALLED WITH THE ARROW FACING TOWARDS THE EXHAUST SIDE,
THE PISTON RINGS MUST BE INSTALLED WITH THE WORD «TOP» OR THE STAMPED MARK
FACING UPWARDS.

Piston rings

* Fit rings «2» and «3» with the word «TOP» facing upwards.
** Position the openings in the rings as shown here.
*** Value «A» of sealing ring inside the cylinder
**** Ring opening
Name
1st Compression
ring
Middle piston ring
Oil scraper ring

Crankcase - crankshaft - connecting rod

Crankcase / countershaft coupling
Besides considering it should match the crankshaft, the crankcase is chosen according to the centre
to centre distance between the seat of the crankshaft and that of the contra-rotating shaft.
Both the centre to centre distance and the pair of gears driving the contra-rotating shaft are divided into
two types (A and B) to be matched (A with A and B with B).
This selection is useful to keep the difference between the working distance of the gears and their
distance without clearance at a given value in order to avoid abnormal noise.
CHAR - 10
B:

CATEGORIES OF COUPLING

Initials Cylinder
A 91.990 - 91.997
B 91.997 - 92.004
C 92.004 - 92.011
D 92.011 - 92.018

SEALING RINGS

Initials Cylinder
A 0.15 ÷ 0.35
A 0.25 ÷ 0.50
A 0.25 ÷ 0.50
Nexus 500
Desc./Quantity
43 mm
Piston Play on fitting
91.954 - 91.961 0.029 - 0.043
91.961 - 91.968 0.029 - 0.043
91.968 - 91.975 0.029 - 0.043
91.975 - 91.982 0.029 - 0.043
Piston Play on fitting
0.5
0.65
0.65
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