Trimmer

Stihl FS 40

2-Stroke · Also known as: FS 40 C

The Stihl FS 40 is a 27.2cc 2-stroke curved-shaft trimmer positioned just above the FS 38 in Stihl's consumer range, with a slightly refined handlebar configuration. Suited for residential grass trimming and lawn edging. The FS 40 runs a Zama carburetor; fuel system maintenance — primer bulb, fuel filter, and fuel lines — accounts for the majority of service calls. It uses a bump-feed .080" trimmer head. The FS 38, FS 40, and FS 45 share engine and filter components, ensuring strong parts availability across the entire entry range.

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: 0000 400 7000, 4144 124 2800, 0000 350 3502, 4144 120 0608, 4226 121 2700, 4144 358 0800, 4006 710 2126
Model Family: FS 38, FS 40, FS 45, FS 55
Last Reviewed: 2026-05-20
Data Confidence: Aftermarket-confirmed
Sources Consulted: OEM part references, Aftermarket catalog cross-references, Retailer fitment listings

ℹ See also: FS 38, FS 45, FS 55 — parts are often interchangeable within this family.

Quick Fitment

Part Type	OEM / Spec	Common Option	Confidence
Spark Plug	0000 400 7000	NGK BPMR7A	Medium · 2026-05-20
Air Filter	4144 124 2800	OEM 4144 124 2800	Low · 2026-05-20
Fuel Filter	0000 350 3502	OEM 0000 350 3502	Low · 2026-05-20
Carburetor	4144 120 0608	Zama C1M-S267D	Medium · 2026-05-20
Primer Bulb	4226 121 2700	Zama 0057004	Medium · 2026-05-20
Trimmer Head	4006 710 2126	Oregon 55-265	Medium · 2026-05-20
Fuel Line Kit	4144 358 0800	Hipa 4144 358 0800	Medium · 2026-05-20
Trimmer Line	.080" 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 Stihl FS 40, 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 0000 400 7000, 4144 124 2800, 0000 350 3502, 4144 120 0608 and match the removed part before choosing a listing.

Common aftermarket option

Cross-check aftermarket listings such as NGK BPMR7A (spark plug), Zama C1M-S267D (carburetor), Zama 0057004 (primer bulb) against the OEM number and dimensions.

Best for annual tune-up

Bundle spark plug, air filter, fuel filter when servicing the Stihl FS 40 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 FS 38 or FS 45? Parts may interchange with FS 38, FS 45, FS 55, but verify the serial range, OEM number, and physical part details before ordering.

Should I buy OEM or aftermarket parts for the Stihl FS 40? 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 FS 40? 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

OEM0000 400 7000Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Dimensions: 0.7mm gap

Brand	Part #
NGK	BPMR7A	Best for annual tune-upAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.
Champion	RCJ6Y	Best for annual tune-upAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Air Filter

OEM4144 124 2800Confidence: Low · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also fits FS 50, FS 70, KM 56

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.

Fuel Filter

OEM0000 350 3502Confidence: Low · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: 3/16" ID in-tank filter

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.

Carburetor

OEM4144 120 0608Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Zama C1M-S267D; also fits FS 50, FS 56

Brand	Part #
Zama	C1M-S267D	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Primer Bulb

OEM4226 121 2700Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20

Brand	Part #
Zama	0057004	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.
Hipa	G002-H	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

OEM4144 358 0800Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Includes fuel pickup line and return line; also fits FS 50, FS 56, FS 70

Brand	Part #
Hipa	4144 358 0800	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Trimmer Head

OEM4006 710 2126Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: AutoCut C 6-2; bump-feed; .080" line

Brand	Part #
Oregon	55-265	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: .080" 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	490-080-0100	Best overallAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.