Trimmer

Husqvarna 525LS

2-Stroke

The Husqvarna 525LS is a 25.4cc 2-stroke professional straight-shaft trimmer and the loop-handle variant of the 525L, designed for operators who prefer a single-hand grip for production trimming. Mechanically identical to the 525L, it shares all service parts. The loop handle suits open-area production trimming where the operator moves quickly and changes direction frequently. Maintenance matches the 525L: monthly fuel system inspection, air filter service, and gearhead grease repacking under daily commercial use. Fuel filter and primer bulb are primary consumables.

See a wrong fitment? Report a correction.

Verify before ordering: Fitment can vary by serial number, production date, region, and sub-model. Match the OEM number and physical dimensions before ordering.

Equipment: Trimmer · 2-Stroke
Covered Parts: Spark Plug, Air Filter, Fuel Filter, Carburetor, Primer Bulb, Fuel Line Kit, Trimmer Head, Trimmer Line
OEM References: 584968101, 576401601, 591375401, 584901401, 503936601, 597967305, 537388101
Model Family: 525L, 525LK, 525LS, 525LST
Last Reviewed: 2026-05-20
Data Confidence: Aftermarket-confirmed
Sources Consulted: OEM part references, Aftermarket catalog cross-references, Retailer fitment listings

ℹ See also: 525L, 525LK, 525LST — parts are often interchangeable within this family.

Quick Fitment

Part Type	OEM / Spec	Common Option	Confidence
Spark Plug	584968101	NGK CMRYA	Medium · 2026-05-20
Air Filter	576401601	Stens 605-730	Medium · 2026-05-20
Fuel Filter	591375401	Stens 610-035	Medium · 2026-05-20
Carburetor	584901401	Zama C1Q-EL24	Medium · 2026-05-20
Primer Bulb	503936601	Zama BG-00-4	Medium · 2026-05-20
Trimmer Head	537388101	Oregon 55-282	Medium · 2026-05-20
Fuel Line Kit	597967305	Stens 115-627	Medium · 2026-05-20
Trimmer Line	.095" diameter, round	Oregon 22-895	Low · 2026-05-20

Tune-Up Kit

Common service bundle: spark plug, air filter, fuel filter, carburetor, primer bulb, fuel line kit.

Maintenance Interval

Inspect filters and fuel lines each season, replace spark plugs during annual service, and service carb/fuel-system parts when starting or idle symptoms appear.

Before You Buy

Confirm the full model is Husqvarna 525LS, not just the family name.
Check serial number, production date, and regional variant before ordering.
Match the old OEM number stamped on the removed part when available.
Compare dimensions, plug gap, thread, fuel line diameter, or chain pitch/gauge where applicable.

Common Mistakes

Ordering from a family listing without checking the exact sub-model.
Buying a kit that includes the headline part but wrong gaskets, lines, or bulb size.
Choosing the wrong carburetor revision when multiple versions were used.
Assuming all fuel line kits use the same diameter and routing.
Installing the correct plug number with the wrong gap.

Symptoms Map

Won't start

Spark plug, fuel filter, primer bulb, carburetor

Starts then dies

Fuel filter, fuel line kit, carburetor

Bogs under throttle

Air filter, carburetor, spark plug gap

Primer will not fill

Primer bulb, fuel line routing, in-tank filter

Replacement Options

Best OEM equivalent

Start with OEM references 584968101, 576401601, 591375401, 584901401 and match the removed part before choosing a listing.

Common aftermarket option

Cross-check aftermarket listings such as NGK CMRYA (spark plug), Stens 605-730 (air filter), Stens 610-035 (fuel filter) against the OEM number and dimensions.

Best for annual tune-up

Bundle spark plug, air filter, fuel filter when servicing the Husqvarna 525LS at the start of the season.

Best if replacing fuel system

Compare the fuel filter, carburetor, primer bulb, fuel line kit together so line routing, bulb size, filter style, and carburetor connections match.

Best budget kit

Use kit listings only when every included part matches this model page; cheap kits often mix correct headline parts with wrong bulbs, lines, or gaskets.

FAQ

Does this fit 525L or 525LK? Parts may interchange with 525L, 525LK, 525LST, but verify the serial range, OEM number, and physical part details before ordering.

Should I buy OEM or aftermarket parts for the Husqvarna 525LS? Use OEM when the part controls fuel metering, ignition, or safety. Aftermarket kits can be useful for routine filters, bulbs, plugs, and tune-up bundles when the OEM number and dimensions match.

How do I avoid ordering the wrong carburetor for the 525LS? Match the carburetor number stamped on the removed unit, then compare linkage, choke setup, primer routing, gasket stack, and fuel-inlet direction.

What should I check before replacing fuel-system parts? Photograph the old fuel-line routing, match line diameter and filter style, and compare primer bulb size before buying a kit.

Spark Plug

OEM584968101Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Dimensions: 0.6mm gap

Brand	Part #
NGK	CMRYA	Best for annual tune-upAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Air Filter

OEM576401601Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also fits 525L, 525LST, 525RJD; secondary filter element 577851501

Brand	Part #
Stens	605-730	Best for annual tune-upAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Fuel Filter

OEM591375401Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also fits 525L, 525LST series

Brand	Part #
Stens	610-035	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Carburetor

OEM584901401Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also fits 525L, 525LST, 525ES, 325HE3, 325HE4

Brand	Part #
Zama	C1Q-EL24	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Primer Bulb

OEM503936601Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20

Brand	Part #
Zama	BG-00-4	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Fuel Line Kit

OEM597967305Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Fuel hose assembly; also fits 525L, 525LK

Brand	Part #
Stens	115-627	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Trimmer Head

OEM537388101Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: T35 Tap Advance; straight shaft; bump-feed .095" line

Brand	Part #
Oregon	55-282	Best overallAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Trimmer Line

OEMSpec-based fitmentConfidence: Low · Source: Inferred

Reviewed: 2026-05-20
Dimensions: .095" diameter, round

Brand	Part #
Oregon	22-895	Best overallAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.
Arnold	490-095-0100	Best overallAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.