17 ENGINE
17.4.15 Checking/measuring the piston
306591-10
- 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 the piston ring is stiff:
- 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.
153
- Measure the piston at the piston skirt, parallel to the gudgeon pin,at a distance
ofG.
Guideline
Distance
G
Piston - diameter
Size I
Size II
•
Info
7 mm (0.28 in)
94.93 ... 94.96 mm (3.7374 ...
3.7386 in)
94.94 ... 94.97 mm (3.7378 ... 3.739 in)
I
Piston dimensions
O
are marked on the piston head.
17.4.16 Checking the piston ring end gap
304694-10
- Remove the piston ring from the piston.
- Place the piston ring in the cylinder and align with the piston.
Guideline
I
Below the upper edge of the cylinder 110 mm (0.39 in)
- Using special tool
0,
measure the end gap.
Guideline
Piston ring end gap
Compression ring
I
:e; 1.00 mm (:e; 0.0394 in)
Oil scraper ring
I
:e; 1.20 mm (:e; 0.0472 in)
I
Feeler gauge (590290411 00) (
a
p. 229)
If the end gap is greater than the specified value:
- Check/measure the cylinder. (
a
p. 152)
If cylinder wear lies within the specified tolerance:
- Change the piston ring.
- Mount the piston ring with the marking facing upward.
Summary of Contents for FS 450 2015
Page 1: ...PIONEERING SINCE 1903 REPAIR MANUAL2015 FS 450 Art no 3403022en Husqvarna MOTORCYCLES ...
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