SHERCO 2015 450 SEF-R Workshop Manual page 26

Checking individual parts
Piston wear:
• With the help of a micrometer, measure the
outside diameter [A] of piston 15 mm [B] above the
bottom of the piston and at a right angle in relation
to the piston pin.
If the outside diameter of a piston is below the limit,
replace it
Piston 450 SEF-R = 94.93 - 94.95
Ring/ring groove clearance:
• Check the base of the ring in order to verify that
the grooves do not show uneven wear.
• Once the rings are properly set in their grooves,
perform several measurements with a thickness
gauge to determine the ring/ring groove clearance
Top ring:
Oil scraper ring: 0.020-0.055 mm
End gap
Top ring:
Inspection for wear of the connecting rod,
piston pin, and piston:
• Visually control the installed securing clip.
If it seems weakened or distorted, replace it.
If the groove of the pinhole is excessively worn,
replace the piston.
• Measure the diameter of the piston pin by
means of a micrometer. If wherever along the line,
the diameter of the piston pin happens to be inferior
to the limit, replace the shaft.
• Measure the diameter of the two piston pinholes
in the piston and the inner diameter of the connec-
ting rod bushing. If one of the diameters of the
holes measured on the piston is incorrect, change
the piston.
If the diameter of the connecting rod bushing is
incorrect, replace the connecting rod.
Diameter of the piston pin: 19.995-20.000 mm
Diameter of the piston pin hole: 20.004-20.009 mm
Inner diameter of the connecting rod bushing: 20.007-20.013 mm
26
0.020-0.065 mm
Limit 0.13 mm
Limit 0.13 mm
0.2-0.3 Limit 0.5 mm
450 SEF-R
B
A