Husqvarna 131R Workshop Manual page 44

Item The piston is not sufficiently lubricated, ex-
ample 1
1 The piston has small to moderate score
marks usually in front of the exhaust port.
Very high temperature makes the piston ma-
terial come off along the piston skirt and cylin-
der bore.
Usually the piston ring is not damaged and
moves freely in the ring groove. There can al-
so be scores on the inlet side of the piston.
Item The piston is not sufficiently lubricated, ex-
ample 2
2 A piston ring that is almost blocked or fully
blocked in its groove does not seal against
the cylinder wall. This results in intense tem-
perature increases in the piston. There can
also be scores along the piston skirt on the
inlet and on the exhaust sides.
Item Scores on the piston because of heavy car-
bon contamination
3 This piston damage starts at the exhaust port.
Carbon particles loosen and stay between the
piston and the cylinder wall. Typical for this
piston damage is brown or black discoloration
of the piston skirt.
44 - Repair instructions
Cause
The carburetor is incorrectly
adjusted.
The engine speed is higher
than the recommended
max. speed.
Incorrect oil mixture in the
fuel.
Too low octane fuel.
Cause
Incorrect oil mixture in the
fuel.
Too low octane fuel.
Air leaks. Damaged fuel
hose. Inlet gasket leaks.
Damaged distance piece or
inlet manifold.
Air leakage in the engine
body. Crankshaft seals
leaks. Cylinder and crank-
case gaskets leaks.
Unsatisfactory mainte-
nance. Dirty cooling fins on
the cylinder. Blocked air in-
take on the starter.
Blocked spark arrester
screen in the muffler.
Cause
Incorrect type of two-stroke
oil or gasoline.
Incorrect oil mixture in the
fuel.
The carburetor is incorrectly
adjusted.
Procedure
Examine and adjust the car-
buretor.
Change to a fuel with the
correct oil mixture.
Change to a higher octane
fuel.
Procedure
Change to a fuel with the
correct oil mixture.
Change to a higher octane
fuel.
Replace the damaged
parts.
Replace damaged gaskets
and shaft seals.
Clean the cooling fins and
the air intake.
Clean or replace the spark
arrester screen.
Procedure
Replace the fuel.
Change to a fuel with the
correct oil mixture.
Adjust the carburetor.
675 - 002 - 23.04.2018