Control; Cylinder,Piston - Husqvarna 181 Workshop Manual

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Cylinder, Piston
Removal
Lift off the cylinder cover. Remove the throttle push rod, fuel hose and choke
control from the carburetor. Remove the spark plug protector, and the spark
plug from the cylinder.
L o
the screw that connects the air filter holder to the
c r
Loosen the four screws retaining the cylinder by means of Allen key No.
5025057-01.
Loosen also the two screws for the silencer support.
Lift the cylinder with silencer and carburetor.
To facilitate removal, the piston should be at the bottom dead centre.
Put a clean rag inio the crankcase opening to protect the crankcase from the
ingress of dirt, etc.
Remove the circlips on the wristpin with a pair of flat hose ~liers and ~ush out
the wristpin.
Remove the silencer and the carburetor parts from the cylinder. Clean the
external surface of the carburetor of dirt and sawdust. Scrape off carbon
deposits from the exhaust port and combustion chamber.
Control
Check the following before assembly, and take the measures required:
Broken cooling fins, damaged threads or broken stud
In case of severe damages, exchange the cylinder.
at exhaust port. Restore the thread by means of HeIi-Coil inserts.
Seizure marks in the cylinder wall (especially at
Polish the marks with a fine emery clotch to remove
exhaust port). aluminium deposits.
If the marks are deep, exchange cylinder and piston.
Surface of the cylinder wall worn (esp. at the top). Exchange cylinder and piston.
Seizure marks on the piston. Polish the marks carefully with a fine file or emery cloth.
Before fitting the piston, polish the cylinder wall as stated
above. If the marks are deep, exchange the piston and, if
necessary, the cylinder.
Piston rings stuck in the groove. Remove the piston rings carefully and clean the grooves
completely before mounting the rings.
Check the wear of the piston rings by placing them in the bottom
of the cylinder. The gap between the ends of the ring should
be 2.8 mm max.
Check that the rings are still springy.
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