Husqvarna 343R, 345RX, 343F, 345FX, 345FXT manual Service tips, Defect, Cylinder and piston, Cause

Cylinder and piston 6

Larger, harder particles that enter the engine cause serious damage to the under- side of the piston skirt.

Cause:		Action:
•	Air filter damaged or missing.	Fit a new air filter.
•	Parts from the carburettor or intake	Regular service and inspection.
	system have come loose and
	entered the engine.

Extensive damage to the lower part of the piston’s inlet side.

Service tips
Defect:		Action:
Broken cooling fins, damaged threads or sheared bolts by		In severe cases – replace the cylinder.
the exhaust port.		Repair the threads using Heli-Coil.
Seizure marks in the cylinder bore (especially by the		Polish the damaged area using a fine grade emery cloth
exhaust port).		so that the coating of aluminium disappears.
		With deep seizure score marks the piston and cylinder
		should be replaced.
Surface coating in the cylinder bore worn out (primarily at		Replace the cylinder and piston.
the top of the cylinder).
The piston shows signs of seizure score marks.		Carefully polish the damaged area using a fine file of fine
		grade emery cloth. Before the piston is refitted the cylinder
		should be polished as above. With deep score marks the
		piston and cylinder should be replaced.
Piston ring burnt in its groove.		Carefully loosen the piston rings and clean the groove well
		before refitting. Carbon deposits in the groove impair the
		important heat transfer between the piston and cylinder.
		NOTE!
		Be careful with the lower edge of the piston ring
		groove. If this is damaged, or if carbon deposits
		remain, the compression pressure can leak through.
	Check the wear on the piston ring by placing it in the lower
	part of the cylinder.
Bolts much too tight in the aluminium material.	Position a suitable punch on the bolt head and give a few
	sharp knocks with a hammer. If the bolt still does not loosen,
	repeat the procedure.

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