Analysis And Actions - Husqvarna 545RXT AT Workshop Manual

Cylinder and piston

14.5 Analysis and actions

With help of the illustration and the accompanying description, note the reasons for the breakdown, repair the
damage and take the actions required to prevent the same thing happening again.
14.5.1 Insufficient lubrication
The piston has small to medium size score marks usually
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.
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 air/fuel mixture.
Incorrect oil mixture in the fuel.
Too low octane fuel.
Small to medium size scores primarily in the middle of
the exhaust port.
Action:
Check engine for leakage, check "H" level in CST and
perform an engine adjustment according to 9.9.
Change the fuel.
Change to a higher octane fuel.
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