Husqvarna 343F, 345FX, 345FXT, 343R, 345RX manual Foreign objects, Cause

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Cylinder and piston

Small score marks and a matt, grey surface on the piston’s inlet side caused by fine dust particles.

Foreign objects

Everything other than clean air and pure fuel that enters the engine’s inlet port causes some type of abnormal wear or damage to the cylinder and piston.

This type of increased wear shows on the piston’s inlet side starting at the lower edge of the piston skirt.

The damage is caused by badly filtered air that passes through the carburettor and into the engine.

Inlet side.

Particles of dust and dirt from carbon-like deposits on the top of the piston and in the piston ring groove. The piston ring sits firmly in the groove. Piston material has been worn away.

The lower part of the piston skirt is thinner on the inlet side than on the exhaust side.

Cause:

•Faulty air filter. Small dust particles pass through the filter.

•The filter is worn out due to too much cleaning, whereby small holes have appeared in the material.

•Unsuitable filter maintenance, such as wrong method or wrong cleaning agent. Flock material becomes loose and holes appear.

•Air filter incorrectly fitted.

•Air filter damaged or missing.

Action:

Fit a finer grade filter.

Check the filter carefully for holes and damage after cleaning. Replace the filter if necessary.

Clean more carefully and use the right cleaning agent (such as tepid soapy water).

Change the filter.

Fit the filter correctly.

Fit a new air filter.

The piston scored and worn from the piston ring down on the inlet side.

Larger, softer particles that penetrate into the engine cause damage to the piston skirt under the piston ring as the illustration shows.

Cause:

Action:

•

Air filter incorrectly fitted.

Fit the air filter correctly.

•

Air filter damaged or missing.

Fit a new air filter.

 

 

 

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Contents English Workshop Manual Brushcutter, Trimmer Model 343R, 345RX, 343F, 345FX, 345FXT ContentsGeneral recommendations Starter ContentsDismantling 1StarterStarter AssemblyReplacing the drive dogs Electrical system Checking the ignition spark Electrical system502 71 Tip 502 50 Replacing the spark Plug cover502 54 Heated handles Drive dogsWiring diagram Electrical system Fuel system Air filter Fuel systemFuel filter Tank ventingCarburettor Fuel pumpDismantling Metering unit Carburettor’s designBlending unit Dismantling the carburettor Pump unitFuel system For example, the H-needle is a PositionedLittle shorter than the L-needle Assembling the carburettor Than the L-needle H-needle is a little shorterCheck carefully that the fuel hoses Are not bent or pinched whenBasic setting Carburettor settingsFine adjustment Correctly adjusted carburettor Setting Recommended max. speed must not be exceededTachometer should always be used to find the optimal Idling speed T-screwAdjusting the L-needle Adjusting the H-needle Carburettor adjustment 345RX/FXThrottle RotatingCheck for wear on pins a and B Tip Page Centrifugal clutch 502 21 Centrifugal clutchDo not lose the sleeve bearings found in the clutch shoes Centrifugal clutch502 11 Clutch drumChange the bearings in the clutch housing if necessary Page Angle gear Let the small circlip around the axle remain Angle gearInput axle with pinion must be dismantled first 503 97503 80 ShaftCylinder and piston Cylinder and piston When the valve is fitted the small hole must face outwards Turn the valve the right way when fittingDecompression valve Inlet manifold Cleaning, inspection Insufficient lubrication Analysis and actions Cause Action Piston scoring caused by heavy carbon deposits Piston ring breakage Piston damage caused by a too high engine speedCause Foreign objectsDefect Action Service tipsWear tolerances Crankshaft and crankcase Crankshaft and crankcase 502 52 Crankshaft and crankcaseInspecting Crankshaft Assembly Press down the sealing plates as Leakage testing CrankcaseFar as possible between the bolts To ensure a proper seal503 55 Husqvarna E-Tech
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