Cylinder And Piston - Derbi GPR 125 Racing Workshop Manual

3. Measurement:
- Distortion
Outside that specified => Rectify.
Cylinder head distortion:
less than 0.03mm
Steps for measuring the distortion and rectification:
- Place a ruler (1) and a thickness calliper (2) on the head
cylinder surface, as in the figure to the side.
- Measure the distortion.
- If the distortion is outside that specified, rectify the cylinder
head.
- The lines in the picture correspond to the different directio-
ns that need to be checked with the ruler.
- Lay a 400 – 600 file on a flat surface and rectify the cylin-
der head surface by filing with a figure eight movement.
N.B.
TURN THE CYLINDER HEAD SEVERAL TIMES TO AVOID AN
EXCESSIVELY UNEVEN REMOVAL OF MATERIAL.
C C
YLINDER AND PISTON YLINDER AND PISTON
1. Inspect:
- Cylinder and piston walls.
Vertical scratches=> Rectify or replace the cylinder and
the piston.
2. Measurement:
- Cylinder-piston play
Steps for measuring:
Step 1:
- Measure cylinder diameter "C" with an internal calliper.
N.B.
MEASURE THE DIAMETER "C" OF THE CYLINDER ACROSS
AND AT A RIGHT ANGLE TO THE CRANKSHAFT. THEN CAL-
CULATE THE AVERAGE MEASUREMENT.
56