Kohler 12-098-10 lawn mower starter motor | 12V 10-tooth | single-cylinder air-cooled

12V replacement starter motor reference for Kohler Command vertical-shaft single-cylinder air-cooled engines. Kohler identifies 12-098-10 as a starter motor, and parts catalogs cross-reference it to John Deere AM117130 / AM120729 and other equivalent numbers for John Deere STX-series lawn tractors.

OEM and Search References

• Primary reference: 12-098-10 (Kohler)
• Substitute reference: Kohler 12-098-17-S / 25-098-03 / 25-098-04 / 25-098-05 / 25-098-06 / 25-098-07 (incl. -S suffix); John Deere AM117130 / AM120729 / AM122435 / AM130407 / AM132818; Lester 5775; J&N 410-21040; Stens 435-511; Oregon 33-722; Rotary 9997; Cargo 113017; United Tech 5667140-M030SM; Wilson 91-09-1067 / 71-09-5775
• Equipment reference: Kohler Command vertical-shaft single-cylinder air-cooled 12.5–16HP engines: CV12.5 / CV13 / CV14 / CV15 / CV16 (incl. S versions), CV460 / CV461 / CV490 / CV491; typical equipment: John Deere STX30 (9HP) / STX38 (12.5–14HP) / STX46 (14HP) lawn tractors, Sabre series.
• Buyer search terms: Kohler 12-098-10 starter motor, 12-098-10 starter, John Deere STX38 starter, STX46 starter, John Deere AM117130 starter, Kohler CV15 starter, 10 tooth starter, 12V lawn tractor starting motor.

Reference Specifications

• System voltage: 12V, as stated in the product title.
• Pinion: 10 teeth, reported by compatible replacement listings cross-referenced to 12-098-10.
• Pinion outer diameter: 30.7 mm (1.209 in); mounting: two 8.0 mm plain holes; body length: 181 mm (7-1/8 in); field shell length: 96.7 mm; battery terminal located on the field shell; type: PMDD permanent-magnet direct drive, approx. 2.3 kg.
• Rotation: counterclockwise (CCW, viewed from the pinion end), reported by compatible replacement listings cross-referenced to 12-098-10.
• Important identification note: this unit shares its platform with the 13-tooth 12-098-05 but uses the small-diameter 10-tooth pinion — the two are not interchangeable. These details are not confirmed Kohler factory specifications; match them against the removed unit before ordering.

Fitment and Purchase Checks

• Catalog-listed equipment: Kohler CV12.5–CV16 vertical-shaft engines and John Deere STX / Sabre tractors listed above. Confirm engine model and spec number, existing starter number, voltage, pinion tooth count (10 teeth), rotation, mounting pattern, terminal layout, and physical dimensions before purchase. Exact 12-098-10 length, width, and height have not been verified and are omitted.

For Agricultural Buyers and Distributors

• This listing is organized for outdoor power equipment procurement teams, repair shops, and parts distributors searching by equipment model and OEM reference. Listed under both the Kohler and John Deere numbers, it serves the high-volume STX-series repair market; stocking it alongside the 13-tooth 12-098-05 covers the full Command single-cylinder range. For quotation, 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

Kohler Command CV-series singles power a huge fleet of John Deere STX30 / STX38 / STX46 and Sabre lawn tractors, and the starter is among the first electrical parts to wear out on machines that start and stop dozens of times per session. When it fails, the tractor sits idle while the owner sorts through look-alike numbers - and the 10-tooth versus 13-tooth confusion makes a wrong purchase likely. This starter reproduces the original pinion, mounting pattern, and terminal position exactly, so a workshop replaces the unit as a whole and moves on. For parts distributors, it fills steady replacement demand across a broad installed base, and stocking it next to the 13-tooth 12-098-05 covers the full Command single-cylinder range with just two SKUs.

How It Works: Power and Engagement

The unit is a permanent-magnet direct-drive (PMDD) design: a copper-wound armature spins inside a ring of ferrite magnets, and the 10-tooth pinion is fixed directly to the armature shaft, so cranking response is immediate when current flows. Turning the key energizes the solenoid first, sliding the 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. Rotation is counter-clockwise viewed from the pinion end, matching the Kohler flywheel. The two plain 8 mm mounting holes hold 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 high-hour starters.
• Windings: copper wire for low resistance and good heat rejection during repeated start cycles.
• Magnets: ferrite field magnets, stable at under-hood temperatures and resistant to demagnetization.
• Brushes and commutator: sized for long service life inside a dust-tight brush holder that keeps grass grit away from the contact area.
• Housing: coated shell that withstands rain, grass debris, and the wash-down exposure typical of lawn-tractor service.

Problems It Solves

STX-series tractors usually arrive 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. 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: this 10-tooth unit shares its platform with the 13-tooth 12-098-05, and the two look alike but do not interchange - 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 tractor 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. Production follows ISO 9001, IATF 16949, and CE practices, and consistent cross-references to Lester 5775, John Deere AM117130, and J&N 410-21040 keep ordering by catalog number straightforward and returns low.