Trimmer

Stihl FS 100 R

4-Mix · Also known as: FS 100

The Stihl FS 100 R is a 36.3cc 4-Mix straight-shaft trimmer and a step above the FS 90 in Stihl's professional lineup. The 4-Mix engine runs standard 50:1 premix on a 4-stroke valve train for reduced noise, improved torque, and lower emissions. It runs a Walbro carburetor and is capable of driving rigid brush blades for heavy vegetation management. Valve clearance inspection every 50 hours is an additional maintenance task unique to 4-Mix models. Gearhead grease repacking and fuel system service are performed seasonally under commercial use.

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 · 4-Mix
Covered Parts: Spark Plug, Air Filter, Fuel Filter, Carburetor, Recoil Starter, Ignition Coil, Primer Bulb, Fuel Line Kit, Trimmer Head, Trimmer Line
OEM References: 0000 400 7009, 4180 120 1800, 0000 350 3502, 4180 120 0607, 4180 080 2102, 4180 400 1300, 4226 121 2700, 4180 350 1402, 4002 710 2193
Model Family: FS 90 R, FS 100, FS 110, FS 111 R, FS 130 R, FS 131 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 111 R, FS 130 R, FS 131 R — parts are often interchangeable within this family.

Quick Fitment

Part Type	OEM / Spec	Common Option	Confidence
Spark Plug	0000 400 7009	NGK CMR5H	Medium · 2026-05-20
Air Filter	4180 120 1800	OEM 4180 120 1800	Low · 2026-05-20
Fuel Filter	0000 350 3502	OEM 0000 350 3502	Low · 2026-05-20
Carburetor	4180 120 0607	Zama C1Q-S183	Medium · 2026-05-20
Primer Bulb	4226 121 2700	Zama 0057004	Medium · 2026-05-20
Trimmer Head	4002 710 2193	Oregon 55-266	Medium · 2026-05-20
Recoil Starter	4180 080 2102	Stens 150-570	Medium · 2026-05-20
Ignition Coil	4180 400 1300	OEM 4180 400 1300	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 100 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 0000 400 7009, 4180 120 1800, 0000 350 3502, 4180 120 0607 and match the removed part before choosing a listing.

Common aftermarket option

Cross-check aftermarket listings such as NGK CMR5H (spark plug), Zama C1Q-S183 (carburetor), Stens 150-570 (recoil starter) against the OEM number and dimensions.

Best for annual tune-up

Bundle spark plug, air filter, fuel filter when servicing the Stihl FS 100 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 111 R, FS 130 R, FS 131 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 100 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 100 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

OEM0000 400 7009Confidence: Medium · Source: Aftermarket catalog

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

Brand	Part #
NGK	CMR5H	Best for annual tune-upAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Air Filter

OEM4180 120 1800Confidence: Low · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also fits FS 87, FS 90, FS 110, FS 130

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

OEM4180 120 0607Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Zama C1Q-S183; 4-Mix diaphragm carb

Brand	Part #
Zama	C1Q-S183	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Recoil Starter

OEM4180 080 2102Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Fits FS 90 R, FS 100, FS 110, FS 130 R

Brand	Part #
Stens	150-570	Best overallAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Ignition Coil

OEM4180 400 1300Confidence: Low · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Fits FS 90 R, FS 100, FS 110, FS 130 R

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

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

OEM4180 350 1402Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Includes fuel pickup line and return line; replaces 4180 358 7700

Brand	Part #
Hipa	4180 350 1402	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Trimmer Head

OEM4002 710 2193Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: AutoCut C 26-2; bump-feed

Brand	Part #
Oregon	55-266	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.