Checking/Measuring The Piston - KTM 450 SX-F EU Repair Manual

301ENGINE - WORK ON THE INDIVIDUAL PARTS
301249-10
40037&-10
Cbeckin&(measurinl tile piston
- The cylinder size is marked on the cylinder collar.
- Using a straightedge and the special tool, check the sealing area of the cylinder
head for distortion.
I
Feeler gauge
(59029041100) ( ..
p.
230)
Cylinder/cylinder head - distortion of
sealing area
s
0.10
mm
(S 0.0039
in)
>
If the measured value does not meet specifications:
- Change the cylinder.
- Check the piston sliding surface for damage.
>
If the piston sliding surface is damaged:
- Replace the piston and, if necessary, the cylinder.
- Check that the piston rings move easily in the piston ring grooves.
>
If a piston ring exhibits excessive resistance:
- Clean the piston ring groove.
• Tip
I
An old piston ring can be used to clean the piston ring groove.
- Check the piston rings for damage.
>
If the piston ring is damaged:
- Replace the piston ring.
• Info
I
Mount the piston ring with the marking facing upward.
- Check the piston pins for discoloration or signs of wear.
>
If the piston pin shows severe discoloration/signs of wear:
- Replace the piston pin.
- Place the piston pin in the connecting rod and check the seating for play.
>
If the piston pin seating has excessive play:
- Replace the connecting rod and piston pin.
- Measure the pistons at the piston skirt, perpendicular to the piston pin.
Guideline
Piston - diameter
Size I
96.960 ... 96.970
mm
(3.81732 ...
3.81771
in)
Size
II 96.971...96.980
mm
(3.81775 ...
3.8181
in)
•
Info
I
Piston dimensions are marked on the piston head.
142