Honda 31210-ZE1-023 lawn mower starter motor | 12V 17-tooth | single-cylinder air-cooled

12V replacement starter motor reference for Honda GX140 / GX160 single-cylinder air-cooled general-purpose engines. Honda identifies 31210-ZE1-023 as a starter motor; the unit is a Mitsuba-built starter also listed under Mitsuba SM-11, and the same structure is widely reused by 168F-type clone engines.

OEM and Search References

• Primary reference: 31210-ZE1-023 (Honda)
• Substitute reference: Mitsuba SM-11 / SM11; Lester 18524; Stens 435-070; PSH 400.040.174; Delco Remy RS41245; Cargo 113671; Woodauto STR75412; PIC 191-114; EMS 49-8996; Andre Niermann 11023; Nastra 18524
• Equipment reference: Honda GX140 / GX160 single-cylinder air-cooled 5.0–5.5HP general-purpose engines (electric-start versions such as GX160QXE2); 168F and similar clone engines; typical equipment: portable generators, water pumps, mini tillers, high-pressure washers, compact rollers and other small-engine equipment.
• Buyer search terms: Honda GX160 starter motor, 31210-ZE1-023 starter, GX140 starter, Mitsuba SM-11 starter, 168F starter motor, 17 tooth starter, generator starter motor, water pump electric start replacement.

Reference Specifications

• System voltage: 12V, as stated in the product title.
• Power: 0.4 kW, reported by compatible replacement listings cross-referenced to 31210-ZE1-023.
• Pinion: 17 teeth, reported by compatible replacement listings cross-referenced to 31210-ZE1-023.
• Pinion outer diameter: 39.3 mm (1.547 in); flange diameter: 55.5 mm; mounting: two 7 mm plain holes; main terminal: B+ (M6); structure: Mitsuba integrated-solenoid type (PMDD / OSGR), approx. 1.6 kg.
• Rotation: counterclockwise (CCW, viewed from the pinion end), reported by compatible replacement listings cross-referenced to 31210-ZE1-023.
• Important identification note: the 17-tooth pinion and integrated solenoid are the identification features of this unit — do not confuse it with the 14-tooth Denso OSGR starter used on Honda GX340 / GX390. These details are not confirmed Honda factory specifications; match them against the removed unit before ordering.

Fitment and Purchase Checks

• Catalog-listed equipment: Honda GX140 / GX160 and 168F-type clone engines listed above. Confirm engine model and type code, existing starter number, voltage, pinion tooth count (17 teeth), rotation, mounting pattern, terminal layout, and physical dimensions before purchase. Exact 31210-ZE1-023 length, width, and height have not been verified and are omitted.

For Agricultural Buyers and Distributors

• This listing is organized for general-purpose engine procurement teams, repair shops, and parts distributors searching by engine model and OEM reference. The GX160 / 168F platform is one of the highest-volume small-engine platforms worldwide (generators, pumps, tillers), making this a high-turnover volume SKU. For aquotation, specify the engine model, old-part number, required quantity, and destination. Confirm price, stock, package quantity, and delivery terms with the seller before placing a purchase order.

Product Positioning

The Honda GX140 / GX160 platform - and the countless 168F-type clones built on the same structure - powers portable generators, water pumps, mini tillers, pressure washers and compact rollers across the world's largest small-engine installed base. These machines live outdoors, start dozens of times per day on job sites, and their Mitsuba-built starters are among the first electrical parts to fail. This starter reproduces the original 17-tooth pinion, integrated-solenoid layout, two-hole mounting pattern and B+ terminal exactly, so a workshop replaces the unit as a whole and moves on. For parts distributors, it is a high-turnover volume SKU on one of the biggest replacement markets in the small-engine category, and stocking it next to the 14-tooth Denso OSGR starter for GX340 / GX390 keeps the two GX families clearly separated.

How It Works: Power and Engagement

The unit is a Mitsuba integrated-solenoid design: the solenoid sits directly on the starter body, and turning the key energizes it first, sliding the 17-tooth pinion into mesh with the flywheel ring gear before the main contacts close and apply full battery voltage - the two-step sequence that prevents tooth-on-tooth grinding. The copper-wound armature then spins inside a ring of ferrite magnets, and the pinion is fixed directly to the armature shaft, so cranking response is immediate. Rotation is counter-clockwise viewed from the pinion end, matching the GX flywheel. The two plain 7 mm mounting holes and the 55.5 mm flange locate the pinion-to-ring-gear clearance exactly as the factory unit did, which keeps engagement quiet and complete.

Materials and Durability

• Pinion: hardened steel with a ground tooth profile, resisting the tooth-thinning wear common on daily-cycled equipment.
• Windings: copper wire for low resistance and good heat rejection during repeated start cycles.
• Magnets: ferrite field magnets, stable at engine-bay temperatures and resistant to demagnetization.
• Solenoid: integrated and sealed against dust and water splash, suited to outdoor generators and pumps that sit in the rain.
• Housing: compact coated shell, approx. 1.6 kg, that withstands job-site dust, humidity, and the rough handling typical of rental and contractor equipment.

Problems It Solves

GX160-class equipment usually arrives at the shop with one of four complaints. First, slow cranking that worsens when the engine is hot, caused by weak brush contact or dragging magnets inside the worn original. Second, a grinding or slipping noise from pinion teeth that no longer mesh fully with the ring gear. Third, intermittent no-start from arced or contaminated commutator surfaces after a season of outdoor storage. Fourth, a single click with no cranking from burned solenoid contacts. Replacing the complete starter clears all four in one step instead of chasing parts inside a worn unit. One caution before ordering: the 17-tooth pinion and integrated solenoid are the identification features of this unit - do not confuse it with the 14-tooth Denso OSGR starter used on Honda GX340 / GX390. Count the teeth on the removed pinion before you buy.

Replacement Value for Shops and Distributors

For repair shops, one correctly matched starter returns a generator, pump or tiller to work the same day, with no drilling, tapping, or wiring changes in between. For dealers and distributors, the numbers work: 50-unit minimum order, 7-30 day lead time, 12-month warranty, and unit pricing well below OEM supply channels, leaving room for margin at a competitive shelf price on a fast-moving SKU. Production follows ISO 9001, IATF 16949, and CE practices, and consistent cross-references to Mitsuba SM-11, Lester 18524, and Stens 435-070 keep ordering by catalog number straightforward and returns low.