Husqvarna K770 SmartGuard, Workshop Manual

Page: 43 / 76

6.7.4 To install the decompression valve
1. Clean and examine the sealing washer before you
install the decompression valve.
6.8 Cylinder and piston
6.8.1 To examine the compression of the cylinder
The test shows leakage from the combustion chamber.
1. Operate the engine for some minutes until it is
warm.
2. Close the decompression valve or put in the sealing
plug. Refer to
Servicing tools overview on page 10.
3. Remove the spark plug.
4. Connect the compression tester to the spark plug
hole.
5. Pull the starter rope 5-6 times and read the pressure
on the gauge. Remove the pressure from the
cylinder and do the procedure some more times.
6. Make a note of the average of the tests.
The average for a new engine is approximately 10 bar /
150 psi. Values less than 8 bar / 120 psi show faults with
or on the cylinder, piston or piston rings.
6.8.2 To remove the cylinder
Divide the product at the vibration damping unit for
easier access to the cylinder. Refer to
To remove the
vibration damping units on page 20. Tighten the engine
body in a vise. Use soft guards.
1. Remove the 4 screws and remove the cylinder.
2. Remove the cylinder gasket.
6.8.3 To remove the piston
To remove the piston, use a kit for piston service. Refer
to
Servicing tools overview on page 11. The kit contains
piston ring compressors, a piston stop, and a support
plate for the piston. To remove the wrist pin, use the
wrist pin punch. Refer to
Servicing tools overview on
page 11.
1453 - 001 - 02.04.2020 Repair and servicing - 43