17 ENGINE
Info
Piston size
O
is marked on the side of the piston.
17.4.16 Measuring the piston/cylinder mounting clearance
311622-10
- Check/measure the cylinder. (
a
p. 192)
- Check/measure the piston. (
a
p. 193)
- The smallest piston/cylinder mounting clearance equals the
smallest cylinder bore diameter minus the largest piston
diameter. The largest piston/cylinder mounting clearance
equals the largest cylinder bore diameter minus the smallest
piston diameter.
Guideline
Piston/cylinder - mounting clearance
Size I
0.035 ... 0.057 mm (0.00138
... 0.00224 in)
Size II
0.037 ... 0.060 mm (0.00146
... 0.00236 in)
Wear limit
0.070 mm (0.00276 in)
17.4.17 Checking the piston ring end gap
311618-10
194
- Remove the piston ring from the piston.
- Place the piston ring in the cylinder and align with the piston.
Guideline
Below the upper edge of the 20 mm (0.79 in)
cylinder
- Measure end gap
f)
with a feeler gauge.
Guideline
Piston ring - end gap
Compression ring
I s; 0.40 mm (s; 0.0157 in)
Oil scraper ring
I s; 0.80 mm (s; 0.0315 in)
If the end gap is greater than the specified measurement:
- Check/measure the cylinder. (
�
p. 192)
If cylinder wear lies within the specified tolerance:
- Replace the piston ring.
- Mount the piston ring with the marking facing toward the pis-
ton head.