Husqvarna 340, 345, 346XP,350, 351, 353 manual Decompression valve - pressure testing, removal”

Repair instructions

8

When replacing the cylinder 340, 345: Unscrew the decompression valve. (345) Remove the intake system, see “Air intake system

– removal”.

Model 350 is fitted with a spacer, which is secured using four bolts from the underside. The spacer does not however need to be removed when removing the cylinder.

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 (340, 346XP, 350, 351, 353)

•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 cylinder.

•The cylinder is free from score marks and areas of wear.

•The piston is free from score marks. Small scratches can be polished out with fine emery paper.

•The piston ring is not burnt into its groove.

•Measure piston ring wear. This should not exceed 1 mm. Use the piston to push down the piston ring.

•The needle roller bearing is undamaged.

•The inlet manifold is undamaged.

•Pressure test the decompression valve.

•Also refer to Jonsered’s Analysis guide for piston failures, art. no. 108 07 01-01.

Decompression valve – pressure testing

1

Connect tool 502 50 38-01 to the decompression valve.

2

Pump up the pressure to 80 kPa (0.8 bar).

3

Wait 30 seconds.

4

The pressure should not be less than 60 kPa (0.6 bar).

42 – English