Faults And Causes - Husqvarna 531RS Workshop Manual

14.2 Cleaning and inspection
After dismantling, clean the individual components:
1. Scrape carbon deposits from the top of the piston.
2. Scrape carbon deposits from the cylinder's combus-
tion chamber.
3. Scrape carbon deposits from the cylinder's exhaust
port.
NOTE!
Scrape carefully with not too sharp a tool so
as not to damage the soft aluminium parts.
4. Wash all the components.
5. Inspect the different components for damage and
wear. Check the piston and cylinder for seizure
damage and wear. Also see the "Analysis and ac-
tions" section.
Check the piston ring for wear and damage.
Also see the "Analysis and actions" section.
Check the gudgeon pin.
– If it has blued, it must be replaced.
– If the piston moves too easily both the piston
and the gudgeon pin must be replaced. Check the
needle bearing. If it is discoloured or damaged, it
must be replaced.
Check the circlips. If they exhibit cracks or are
discoloured (caused by overheating), they must be
replaced.

14.3 Faults and causes

Insufficient lubrication 1
The piston has small to medium size score marks usu-
ally in front of the exhaust port. In extreme cases heat
development can be so great that material from the
piston smears along the piston skirt and even in the
cylinder bore. See Figure 5.
Generally the piston ring is undamaged and moves
freely in the ring groove. There can also be scores on
the inlet side of the piston.
Cause
Incorrect carburettor set-
ting. Recommended max.
speed exceeded.
Incorrect oil mixture in the
fuel.
Too low octane fuel.
Action
Check and change the
carburettor setting.
Change the fuel.
Change to a higher
octane petrol.
Fig. 4
Fig. 5
Cylinder and piston
English - 45