BRP-Rotax
REPAIR MANUAL
INSPECTION OF THE PISTON AND CYLINDER SIZING
General
NNOOTTEE
Every new piston has the size classification and a production letter printed on the
top of the piston (piston crown).
NNOOTTEE
Every new cylinder has the size classification stamped on the upper sealing
surface.
Measuring the cylinder diameter:
1. Measure the cylinder diameter 10 mm below the upper edge of the cylinder. This dimension
indicates the selection of the matching piston. If the dimension has reached the wear limit of
54.045 mm, the cylinder must be replaced.
2. Measure the piston diameter as described in chapter 4 “Inspection of the piston diameter”
and install a piston to match the required clearance at 0.060 mm +/- 0.005 mm between pis-
ton and cylinder.
Cylinder classification
Cylinder labeling Cylinder dimension
“A”
54.000 - 54.010 mm
“AB”
54.010 - 54.015 mm
“B”
54.015 - 54.025 mm
Piston classification “f”
Piston labeling
Tolerance field
(mm)
Minimum dimen-
sion (mm)
Maximum dimen-
sion (mm)
“f” 53.95 +0.005 / -0.025 mm
53.925 53.955
“f” 53.96 +0.005 / -0.025 mm
53.935 53.965
“f” 53.97 +0.005 / -0.025 mm
53.945 53.975
“f” 53.98 +0.005 / -0.025 mm 53.955 53.985
“f” 53.99 +0.005 / -0.025 mm 53.965 53.995
Chapter 4
Page 14
Effectivity: 125 MAX evo, Junior MAX
evo, Mini MAX evo, Micro MAX evo
Edition - February 01 2018 /Rev. 0
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