Chainsaw

Husqvarna 445

2-Stroke

The Husqvarna 445 is a 45.7cc 2-stroke chainsaw and the mid-point of Husqvarna's E-series consumer lineup, suited for regular firewood production and occasional felling of medium-diameter trees with 13" to 18" guide bars. The X-Torq engine provides improved torque and fuel economy over the previous generation. The 445 runs a Zama carburetor and accepts the NGK BPMR7A or Champion RCJ6Y spark plug. Parts families overlap with the 435 and 440 within the E-series. Routine maintenance: spark plug, air filter, primer bulb, and fuel system components.

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: Chainsaw · 2-Stroke
Covered Parts: Spark Plug, Air Filter, Fuel Filter, Carburetor, Recoil Starter, Ignition Coil, Primer Bulb, Fuel Line Kit, Chain, Guide Bar
OEM References: 537254402, 544080802, 503446501, 506450401, 544071604, 573935702, 503936601, 544128601
Model Family: 445, 450, 455 Rancher
Last Reviewed: Not yet independently reviewed
Data Confidence: Not yet independently reviewed
Sources Consulted: Evidence source not recorded

Quick Fitment

Part Type	OEM / Spec	Common Option	Confidence
Spark Plug	537254402	NGK BPMR7A	Confidence not assigned · Not yet independently reviewed
Air Filter	544080802	Stens 605-414	Confidence not assigned · Not yet independently reviewed
Fuel Filter	503446501	Stens 610-035	Confidence not assigned · Not yet independently reviewed
Carburetor	506450401	Zama C1M-EL37B	Confidence not assigned · Not yet independently reviewed
Primer Bulb	503936601	Zama BG-00-4	Confidence not assigned · Not yet independently reviewed
Recoil Starter	544071604	OEM 544071604	Confidence not assigned · Not yet independently reviewed
Ignition Coil	573935702	OEM 573935702	Confidence not assigned · Not yet independently reviewed
Fuel Line Kit	544128601	Stens 115-627	Confidence not assigned · Not yet independently reviewed

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 445, 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.
Matching bar length but missing pitch, gauge, or drive-link count.

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

Cuts slowly

Chain pitch/gauge, bar wear, drive links

Replacement Options

Best OEM equivalent

Start with OEM references 537254402, 544080802, 503446501, 506450401 and match the removed part before choosing a listing.

Common aftermarket option

Cross-check aftermarket listings such as NGK BPMR7A (spark plug), Stens 605-414 (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 445 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 chain/bar combo

Match chain specs together, especially pitch, gauge, drive links, and bar mount details.

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

Should I buy OEM or aftermarket parts for the Husqvarna 445? 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 445? 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.

What chain details matter besides bar length? Match pitch, gauge, and drive-link count against the bar stamp, old chain, and drive sprocket. Bar length alone is not enough.

Spark Plug

OEM537254402Confidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed
Dimensions: 0.5mm gap
Variant notes: OEM is Champion RCJ7Y equivalent; also fits 435, 440, 450

Brand	Part #
NGK	BPMR7A	Search AmazonAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.
Champion	RCJ7Y	Search AmazonAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Air Filter

OEM544080802Confidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed
Variant notes: Fits 445 and 450 series; also referenced as 544080803

Brand	Part #
Stens	605-414	Search AmazonAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Fuel Filter

OEM503446501Confidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed
Variant notes: In-tank pickup filter

Brand	Part #
Stens	610-035	Search AmazonAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Carburetor

OEM506450401Confidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed
Variant notes: Zama C1M-EL37B; also fits 445E, 450, 450E

Brand	Part #
Zama	C1M-EL37B	Search AmazonAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Recoil Starter

OEM544071604Confidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed
Variant notes: Also fits 450

Brand	Part #
No aftermarket listing is published for this part yet. Use the OEM reference and verify with a dealer or service manual before ordering.

Ignition Coil

OEM573935702Confidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed
Variant notes: Also fits 435, 440, 450; replaces 505427201, 544243801

Brand	Part #
No aftermarket listing is published for this part yet. Use the OEM reference and verify with a dealer or service manual before ordering.

Primer Bulb

OEM503936601Confidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed

Brand	Part #
Zama	BG-00-4	Search AmazonAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Fuel Line Kit

OEM544128601Confidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed
Variant notes: Includes fuel pickup line and return line

Brand	Part #
Stens	115-627	Search AmazonAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Chain

OEMSpec-based fitmentConfidence: Confidence not assigned · Source: Evidence source not recorded

Reviewed: Not yet independently reviewed
Dimensions: 18", .325" pitch, .050" gauge, 72 drive links
Variant notes: Stock bar length; verify drive link count matches your bar

Brand	Part #
Oregon	95TXL072E	Search AmazonAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Guide Bar