Item
The piston is not sufficiently lubricated, ex-
ample 1
Cause
Procedure
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.
The carburetor is incorrectly
adjusted.
Examine and adjust the car-
buretor.
The engine speed is higher
than the recommended
max. speed.
Incorrect oil mixture in the
fuel.
Change to a fuel with the
correct oil mixture.
Too low octane fuel.
Change to a higher octane
fuel.
Item
The piston is not sufficiently lubricated, ex-
ample 2
Cause
Procedure
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.
Incorrect oil mixture in the
fuel.
Change to a fuel with the
correct oil mixture.
Too low octane fuel.
Change to a higher octane
fuel.
Air leaks. Damaged fuel
hose. Inlet gasket leaks.
Damaged distance piece or
inlet manifold.
Replace the damaged
parts.
Air leakage in the engine
body. Crankshaft seals
leaks. Cylinder and crank-
case gaskets leaks.
Replace damaged gaskets
and shaft seals.
Unsatisfactory mainte-
nance. Dirty cooling fins on
the cylinder. Blocked air in-
take on the starter.
Clean the cooling fins and
the air intake.
Blocked spark arrester
screen in the muffler.
Clean or replace the spark
arrester screen.
Item
Scores on the piston because of heavy car-
bon contamination
Cause
Procedure
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.
Incorrect type of two-stroke
oil or gasoline.
Replace the fuel.
Incorrect oil mixture in the
fuel.
Change to a fuel with the
correct oil mixture.
The carburetor is incorrectly
adjusted.
Adjust the carburetor.
54 - Repair instructions
627 - 002 - 23.04.2018