Decompression Valve - Pressure Testing - Husqvarna 455 Rancher Workshop Manual

6
Remove the bearing from the little end of the con-
necting rod.
If replacing the cylinder:
Remove the intake manifold, see "Air intake sys-
tem – removal".
Cleaning and inspection
Clean all the components, scraping off all traces of
old gasket and carbon from the following places:
• Piston crown
• Top of the cylinder bore
• Cylinder exhaust port
• Decompression valve channel
• Cylinder base and/or crankcase
Check the following:
• The surface coating of the cylinder is not worn
through, especially in the upper part of the cylin-
der.
• The cylinder is free from score marks and areas
of wear.
• The piston is free from score marks. Small scrat-
ches can be polished out with fi ne emery paper.
• The piston ring is freely moving in its groove.
• Measure piston ring wear. This should not
exceed 1 mm. Use the piston to push the piston
ring for correct alignment.
• The needle roller bearing is undamaged.
• The intake manifold is undamaged.
• That the air hoses and impulse hose are unda-
maged.
• Pressure test the decompression valve.
Decompression valve – pressure
testing
1
Connect tool 531 03 06-23 to the decompression
valve.
2
Pump the pressure up to 80 kPa (0.8 bar).
3
Wait 30 seconds.
4
The pressure should not be less than 60 kPa
(0.6 bar).
Repair instructions
35
English –