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Cylinder and piston
Action:
Change to a fuel with the correct oil
mixture.
Change to a higher octane petrol.
Replace damaged parts.
Replace leaking gaskets and shaft
seals.
Clean the cooling fins and air intake.
Clean or replace the spark arrestor
mesh.
Cause:
• Incorrect oil mixture in the fuel.
• Too low octane fuel.
• Air leaks.
Cracked fuel hose.
Leaking inlet gaskets.
Cracked distance piece or inlet
manifold.
• Air leakage in engine body.
Leaking crankshaft seals.
Leaking cylinder and crankcase
gaskets.
• Poor maintenance.
Dirty cooling fins on the cylinder.
Blocked air intake on the starter.
Blocked spark arrestor mesh in
the muffler.
Medium to deep scores along the entire
piston skirt on the exhaust side.
For the best results we recommend Husqvarna two-stroke oil or ready-mixed fuel
that is specially developed for air-cooled two-stroke engines.
Mixing ratio: 1:50 (2%).
If Husqvarna two-stroke oil is not available another good quality two-stroke oil can
be used.
Mixing ratio: 1:33 (3%) or 1:25 (4%).
The piston ring starts to stick or is completely stuck in its groove and has therefore
not been able to seal against the cylinder wall, which has resulted in further,
intensive temperature increases in the piston
Seizure scores along the entire piston skirt on the inlet and exhaust sides.
Action:
Change the fuel.
Change to a fuel with the correct oil
mixture.
Correct the carburettor setting
Medium to deep scores on the exhaust side.
The piston ring is stuck in the groove.
Black discoloration under the piston ring
due to blow-by.
Cause:
• Wrong type of two-stroke oil or
petrol.
• Incorrect oil mixture in the petrol.
• Incorrect carburettor setting.
Piston scoring caused by heavy carbon deposits
Too heavy carbon depositing can cause damage similar to that caused by insuffi-
cient lubrication. However, the piston skirt has a darker colour caused by the hot
combustion gases that are blown past the piston.
This type of piston damage starts at the exhaust port where carbon deposits can
become loose and get trapped between the piston and the cylinder wall.
Typical for this type of piston damage is brown or black discoloration of the piston
skirt.