Trimmer

Stihl FS 85 R

2-Stroke · Also known as: FS 85

The Stihl FS 85 R is a 37.7cc 2-stroke professional-grade straight-shaft trimmer capable of running both bump-feed heads and rigid brush blade attachments. It targets professional landscapers who need more power and versatility than the 27cc homeowner range. The FS 85 runs a Zama carburetor. Under commercial use, fuel system service (filter, primer bulb, fuel lines) and spark plug replacement are performed seasonally at minimum. The FS 85 represents Stihl's pre-4-Mix professional trimmer generation — simpler to service than the 4-Mix FS 90 series and compatible with a wide range of rigid clearing attachments.

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: 1110 400 7005, 4137 124 2800, 0000 350 3502, 4137 120 0608, 4226 121 2700, 0000 930 2803, 4002 710 2191
Model Family: FS 85 R, FS 90 R, FS 100, FS 110, FS 130 R
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 90 R, FS 100, FS 110, FS 130 R — parts are often interchangeable within this family.

Quick Fitment

Part Type	OEM / Spec	Common Option	Confidence
Spark Plug	1110 400 7005	NGK BPMR7A	Medium · 2026-05-20
Air Filter	4137 124 2800	OEM 4137 124 2800	Low · 2026-05-20
Fuel Filter	0000 350 3502	OEM 0000 350 3502	Low · 2026-05-20
Carburetor	4137 120 0608	Zama C1Q-S97	Medium · 2026-05-20
Primer Bulb	4226 121 2700	Zama 0057004	Medium · 2026-05-20
Trimmer Head	4002 710 2191	Oregon 55-993	Medium · 2026-05-20
Fuel Line Kit	0000 930 2803	OEM 0000 930 2803	Low · 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 Stihl FS 85 R, 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 1110 400 7005, 4137 124 2800, 0000 350 3502, 4137 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 C1Q-S97 (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 85 R 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 90 R or FS 100? Parts may interchange with FS 90 R, FS 100, FS 110, FS 130 R, but verify the serial range, OEM number, and physical part details before ordering.

Should I buy OEM or aftermarket parts for the Stihl FS 85 R? 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 85 R? 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

OEM1110 400 7005Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Dimensions: 0.7mm gap
Variant notes: 14mm thread (BPMR7A); 2-stroke engine — do not substitute CMR5H (10mm thread)

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.

Air Filter

OEM4137 124 2800Confidence: Low · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also fits FS 75, FS 80, HS 80, HS 85

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: In-tank pickup 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

OEM4137 120 0608Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Zama C1Q-S97; 2-stroke diaphragm carb

Brand	Part #
Zama	C1Q-S97	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

OEM0000 930 2803Confidence: Low · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Fuel pickup line; also fits FS 75, FS 80, KM 85

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.

Trimmer Head

OEM4002 710 2191Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: AutoCut 25-2; bump-feed

Brand	Part #
Oregon	55-993	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.