Small Engine

Honda GX630

4-Stroke

The Honda GX630 is a 688cc V-twin 4-stroke overhead-valve engine built for commercial and industrial equipment that demands high torque — large generators, riding mowers, welders, and heavy-duty power equipment. Unlike Honda's single-cylinder GX engines, the GX630 uses a V-twin configuration for smoother power delivery and reduced vibration under load. It uses a Keihin carburetor and accepts NGK BPR6ES or Champion RC12YC spark plugs. Oil change intervals every 100 hours and air filter maintenance every 50 hours are standard. Valve clearance should be inspected every 300 hours.

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: Small Engine · 4-Stroke
Covered Parts: Spark Plug, Air Filter, Oil Filter, Fuel Filter, Carburetor
OEM References: 98079-5587G, 17210-Z6L-010, 15400-PLM-A02, 16910-Z6L-003, 16100-Z9E-033
Model Family: GX630, GX660, GX690
Last Reviewed: 2026-05-20
Data Confidence: Aftermarket-confirmed
Sources Consulted: OEM part references, Aftermarket catalog cross-references, Retailer fitment listings

ℹ See also: GX660, GX690 — parts are often interchangeable within this family.

Quick Fitment

Part Type	OEM / Spec	Common Option	Confidence
Spark Plug	98079-5587G	NGK ZFR5F	Medium · 2026-05-20
Air Filter	17210-Z6L-010	Stens 100-005	Medium · 2026-05-20
Fuel Filter	16910-Z6L-003	Stens 120-008	Medium · 2026-05-20
Carburetor	16100-Z9E-033	Stens 520-342	Medium · 2026-05-20
Oil Filter	15400-PLM-A02	Stens 120-722	Medium · 2026-05-20

Tune-Up Kit

Common service bundle: spark plug, air filter, fuel filter, carburetor.

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 Honda GX630, 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.
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

Replacement Options

Best OEM equivalent

Start with OEM references 98079-5587G, 17210-Z6L-010, 15400-PLM-A02, 16910-Z6L-003 and match the removed part before choosing a listing.

Common aftermarket option

Cross-check aftermarket listings such as NGK ZFR5F (spark plug), Stens 100-005 (air filter), Stens 120-722 (oil filter) against the OEM number and dimensions.

Best for annual tune-up

Bundle spark plug, air filter, fuel filter when servicing the Honda GX630 at the start of the season.

Best if replacing fuel system

Compare the fuel filter, carburetor 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 GX660 or GX690? Parts may interchange with GX660, GX690, but verify the serial range, OEM number, and physical part details before ordering.

Should I buy OEM or aftermarket parts for the Honda GX630? 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 GX630? 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

OEM98079-5587GConfidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Dimensions: 0.7-0.8mm gap
Variant notes: NGK ZFR5F equivalent; V-twin engine requires one plug per cylinder (2 total)

Brand	Part #
NGK	ZFR5F	Best for annual tune-upAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Air Filter

OEM17210-Z6L-010Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also fits GX660, GX690, GX630R, GX630RH

Brand	Part #
Stens	100-005	Best for annual tune-upAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Oil Filter

OEM15400-PLM-A02Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also fits GX610, GX620, GX660, GX670, GX690

Brand	Part #
Stens	120-722	Best overallAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Fuel Filter

OEM16910-Z6L-003Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Inline fuel filter; also fits GX660, GX690, GXV630

Brand	Part #
Stens	120-008	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.

Carburetor

OEM16100-Z9E-033Confidence: Medium · Source: Aftermarket catalog

Reviewed: 2026-05-20
Variant notes: Also supersedes 16100-Z9E-023 and 16100-Z9E-003; fits GX630, GX660, GX690 V-twin engines

Brand	Part #
Stens	520-342	Best if replacing fuel systemAmazonAffiliate link Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying.