Selecting The Cylinder; Selecting The Piston - APRILIA SX 125 Service Station Manual

RX SX 125
•
Place the cylinder.
ONLY ASSEMBLE TOGETHER PISTONS AND CYLINDERS
BELONGING TO THE SAME TOLERANCE RANGES.
•
Take out the wrench for piston rings.
•
Working from both sides, fasten the
cylinder crosswise with the four M8
nuts and relevant washers.
TIGHTEN THE FIXING NUTS AGAIN, WHEN THE ENGINE
IS COLD, AFTER THE FIRST 500 KM (310 MI).

Selecting the cylinder

•
The cylinder size code is stamped on
the surface of the cylinder base.
•
Read the cylinder diameter at TDC.
•
The bottom section of the cylinder sur-
face undergoes only slight wear. If the
cylinder TDC area is very worn (it is no
longer bright, rough and sharp), it can
be inferred that the engine has been
working fed on a fuel with too much
sulphur.
Cylinder "A" Diam. 54.000 - 54.010 mm (2.12597
- 2.12637 in) Diam. 54.060 mm (2.12834 in)
Cylinder "AB" Diam. 54.010 - 54.015 mm (2.12637
- 2.12657 in) Diam. 54.065 mm (2.12853 in)
Cylinder "B" Diam. 54.015 - 54.025 mm (2.12657
- 2.12696 in) Diam. 54.075 mm (2.12893 in)

Selecting the piston

Measure the piston diameter with a micrometer, 11.5 mm from the piston bottom edge.
Engine
ENG - 111