Husqvarna 226R Workshop Manual page 39

6
Medium to deep scores along the entire
piston skirt on the exhaust side.
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.
38
Cylinder and piston
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 tem-
perature increases in the piston
Seizure scores along the entire piston skirt on the inlet and exhaust sides.
Cause:
• Incorrect oil mixture in the fuel.
• Too low octane fuel.
• Air leaks.
Cracked fuel hose.
Leaking inlet gaskets.
Cracked distance piece or inlet mani-
fold.
• Air leakage in engine body.
Leaking crankshaft seals.
Leaking cylinder and crankcase gas-
kets.
• Poor maintenance.
Dirty cooling fi ns on the cylinder.
Blocked air intake on the starter.
Blocked spark arrestor mesh in the
muffl er.
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%).
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 be-
come 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.
Cause:
• Wrong type of two-stroke oil or petrol.
• Incorrect oil mixture in the petrol.
• Incorrect carburettor setting.
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 fi ns and air intake.
Clean or replace the spark arrestor mesh.
Action:
Change the fuel.
Change to a fuel with the correct oil mixture.
Correct the carburettor setting