Husqvarna 343F, 345FX, 345FXT, 343R, 345RX manual Piston scoring caused by heavy carbon deposits

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Cylinder and piston

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.

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 temperature increases in the piston

Seizure scores along the entire piston skirt on the inlet and exhaust sides.

Cause:

 

Action:

 

• Incorrect oil mixture in the fuel.

 

Change to a fuel with the correct oil

 

 

 

mixture.

• Too low octane fuel.

 

Change to a higher octane petrol.

•

Air leaks.

 

Replace damaged parts.

 

Cracked fuel hose.

 

 

 

Leaking inlet gaskets.

 

 

 

Cracked distance piece or inlet

 

 

 

manifold.

 

 

• Air leakage in engine body.

 

Replace leaking gaskets and shaft

 

Leaking crankshaft seals.

 

seals.

 

Leaking cylinder and crankcase

 

 

 

gaskets.

 

 

•

Poor maintenance.

 

Clean the cooling fins and air intake.

 

Dirty cooling fins on the cylinder.

 

 

 

Blocked air intake on the starter.

 

 

 

Blocked spark arrestor mesh in

 

Clean or replace the spark arrestor

 

the muffler.

 

mesh.

 

 

 

 

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 become 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:

Action:

• Wrong type of two-stroke oil or

Change the fuel.

petrol.

 

• Incorrect oil mixture in the petrol.

Change to a fuel with the correct oil

mixture.

• Incorrect carburettor setting.

Correct the carburettor setting

 

 

 

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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 502 71 Electrical systemChecking the ignition spark Tip 502 50 Replacing the spark Plug cover502 54 Heated handles Drive dogsWiring diagram Electrical system Fuel system Air filter Fuel systemFuel filter Tank ventingDismantling Fuel pumpCarburettor Blending unit Carburettor’s designMetering unit Dismantling the carburettor Pump unitFuel system Little shorter than the L-needle PositionedFor example, the H-needle is a Assembling the carburettor Are not bent or pinched when H-needle is a little shorterThan the L-needle Check carefully that the fuel hosesFine adjustment Carburettor settingsBasic setting Idling speed T-screw Setting Recommended max. speed must not be exceededCorrectly adjusted carburettor Tachometer should always be used to find the optimalRotating Carburettor adjustment 345RX/FXAdjusting the L-needle Adjusting the H-needle ThrottleCheck 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 Decompression valve Turn the valve the right way when fittingWhen the valve is fitted the small hole must face outwards Inlet manifold Cleaning, inspectionCause Action Analysis and actionsInsufficient lubrication 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 To ensure a proper seal Leakage testing CrankcasePress down the sealing plates as Far as possible between the bolts503 55 Husqvarna E-Tech
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