PIAGGIO 2005 XEVO 400ie, Workshop Manual

Page: 125 / 376

- Pistons and cylinders are classified into categories based on their diameter. The coupling is carried
out in pairs (A-A, B-B, C-C, D-D).
N.B.
REFER TO THE «SPECIFICATIONS» SECTION FOR THE SIZES OF THE CYLINDER AND THE
CYLINDER-PISTON COUPLING CLEARANCES.
Inspecting the piston rings
- Alternately insert the three sealing rings into the
cylinder, in the area where it retains its original di-
ameter. Using the piston, insert the rings perpen-
dicularly to the cylinder axis.
- Make sure that each single sealing ring evenly
adheres to the cylinder liner. If it does not, this
means the ring is worn. Replace it.
- Measure the opening (see figure) of the sealing
rings using a feeler gauge.
- If higher values than those prescribed are meas-
ured, replace the linings.
Check the size of the sealing ring opening:
Compression ring: 0.15 ÷ 0.35 mm. Max. value 0.5 mm
Oil scraper ring: 0.25 ÷ 0.50 mm. Max. value 0.65 mm
Oil scraper ring: 0.25 ÷ 0.50 mm. Max. value 0.65 mm
Rings/housing coupling clearances:
Carefully clean the sealing ring housings.
Place a thickness gauge between the ring and the
housing as shown in the drawing and check the
coupling clearances.
Top ring Standard coupling clearance:
0.01÷0.06 mm
Maximum clearances allowed after use: 0.10
mm
Intermediate ring Standard coupling clear-
ance: 0.02÷0.07 mm
Maximum clearances allowed after use: 0.10
mm
Oil scraper ring Standard coupling clearance:
0.01÷0.06 mm
XEVO 400ie
Engine
ENG - 125