What Engine Is in My Lawn Mower? Not the Hood Badge

ByWoojoong Kim

Probably not one your mower’s manufacturer built. Toro, John Deere, Cub Cadet and Husqvarna all publish spec sheets naming somebody else’s engine — Briggs & Stratton, Kohler or Kawasaki — bolted to their own deck and transmission. Of the seven mower listings compiled below, six carry another company’s engine; the seventh is a Honda, which builds both.

That matters for exactly one practical reason: the engine carries its own model number, and that is the number parts, service manuals, oil capacities and torque specs are indexed under. Briggs & Stratton says so directly. Asked what it needs to find you a replacement engine, its own support page asks for the engine’s “complete, STAMPED Engine Model, Type, and Code numbers” — and lists your equipment’s brand and model number separately, as information that may help.

The engine’s number tells you which part to buy. It does not tell you who will sell it: Briggs prices its own parts, while Kohler and Kawasaki publish no consumer price at all, and on a Kohler-engined Cub Cadet it is the machine maker, not the engine maker, that prices the Kohler part.

Figures and product specifications verified September 2026; next scheduled review March 2027. Nothing on this page is a catalog price, which is why it sits on the six-to-twelve-month specification clock rather than the three-month price clock most pages here carry.

Take one number apart and the point makes itself

The John Deere S100 lawn tractor runs a Briggs & Stratton engine, model 31R977. Six characters. Briggs publishes a chart explaining what each position means, and it is a real decoder, not a marketing sheet:

Position Value What Briggs says it means
First one or two digits31Approximate cubic inch displacement
First digit afterRBasic design series — cylinder construction, ignition, general configuration
Second digit after9Crankshaft orientation. 0–4 and A–G are horizontal; 5–9 and H–Z are vertical
Third digit after7Bearings, reduction gear, auxiliary drive, lubrication. 7 = plain bearing, pressure lubrication
Last digit7Starter type. 7 = electric starter, 12 or 24 volt gear drive, with alternator

Now check it against the machine, which decoding alone does not do.

Briggs’ own store lists 31R977 as a 500 cc vertical-shaft Intek engine rated 17.5 hp. 500 cc converts to 30.5 cubic inches — Briggs numbers the family 31, and the chart’s word is “approximate,” which is what approximate means here: the digits get you to the right engine family, not to a spec you can quote.

The rest lands exactly. A riding mower needs a vertical crankshaft to drive a horizontal blade — the 9 says vertical. It has a battery and a charging system — the final 7 says electric start with an alternator. And John Deere’s own description of the S100 advertises full-pressure lubrication and a cast-iron cylinder liner as selling points; the third digit after the displacement, 7, encodes pressure lubrication independently, in a number stamped on the engine before John Deere wrote a word of copy.

Four separate claims about the machine, confirmed from six characters, using a chart the engine manufacturer publishes for free. That is the whole argument for reading the engine instead of the hood.

The machine brand is hidden in the Type number, not the Model number

The Type number is the reason two mowers with the same engine model are not the same engine.

Briggs’ chart splits engine identity three ways — Model, Type, Code — and defines the middle one like this: the Type number “identifies the engines mechanical parts, color of paint, decals, governed speed, and Original Equipment Manufacturer.”

Read that again. The equipment brand is a field inside the engine’s Type number. Model 31R977 is a 500 cc vertical-shaft engine; the Type is what makes it the John Deere green one, governed to John Deere’s speed, with John Deere’s decals. Change the Type and the same Model number becomes somebody else’s engine.

Which resolves a specific frustration: two mowers can carry “the same Briggs engine” and still take different parts, and neither owner is wrong.

The third number, the Code, is the build date. Briggs reads it as YY-MM-DD plus plant and line — its worked example, code 01061201, is June 12, 2001. So the engine tells you its own age, which is frequently not the age of the machine it came on, and is the number that actually matters when you are working out how much life is left in it.

What the machine makers actually publish

Here is the compiled cross-reference — built by reading each manufacturer’s own spec page — the Cub Cadet from a prior-year listing the company still serves — rather than by asking around. The last column is the one that turned out to be interesting.

Machine brand Example model Engine listed on the maker’s own page Engine model number published there?
John DeereS100 lawn tractorBriggs & Stratton, 17.5 hpNot on the spec page — but Deere prints 31R977 (M31) on MachineFinder, its own used-equipment site
Toro (walk-behind)Recycler 21311“Briggs & Stratton® Ex 140 cc”No — brand, series and displacement only
Cub CadetXT1 LT42Kohler, single cylinder, 541 ccNo
HusqvarnaTS 142Briggs & Stratton, “Endurance Series”, 32.9 cu.inchNo — brand, series and displacement, and the displacement is in cubic inches
Husqvarna (higher lines)Garden tractors, ride-on front mowersKawasaki FR and FS series; FX730V EFI and FJ180V KAI on professional machines — named by Kawasaki, not by HusqvarnaNo
HondaHRN216VKAHonda GCV170, 166 ccYes — because Honda built both
Toro (snow)Power Max 826 OHAE“Toro Premium” 252 cc OHV — a house brandNo such number exists
AriensDeluxe 30 (model 921071)“Ariens AX®”, 301 cc — a house brandNo such number exists
Ariens (lawn)IKON 42 KAWASAKI (model 918002)“Kawasaki® FR651V Twin 21.5 hp/726cc”Yes — and the engine is not Ariens’

Nine listings from six companies, and two of them print the engine’s model number on the machine’s own page. The obvious one is the Honda, whose engine is also a Honda. The second was added on September 8, 2026 and is the one that matters, because the engine is somebody else’s: Ariens’ IKON 42 names “Kawasaki® FR651V Twin 21.5 hp/726cc” in the machine’s feature list and carries FR651V in its specification data. The Honda row is the only other one that prints a number, and it is the easy case — Honda built the engine, so naming it costs Honda nothing. The other seven print the brand. Sometimes the series. Usually the displacement.

But a spec page is not the only thing a machine maker publishes, and John Deere prints the number somewhere else entirely. Its MachineFinder article on the S100 — Deere’s own used-equipment marketplace, whose terms of use, privacy statement and cookie statement all redirect to deere.com — asks “Who Makes the John Deere S100 Engine?” and answers with “the 31R977 (M31) engine … is Briggs and Stratton.” That is the Model and the Type, the two fields the section above says carry the engine’s identity and the machine brand inside it, published by the machine maker rather than the engine maker. It is a blog article and not a specification block, which is why no amount of reading the spec sheet turns it up — but it is Deere’s, and it means the number did not have to come from Briggs’ catalog after all.

And for the parts most owners actually buy, Deere makes the engine number unnecessary. Its own Replacement Parts Guide for the S100 — document GX571641, released March 2023 — lists them under Deere’s own part numbers with a “CLICK PART NUMBER TO BUY” instruction: air filter MIU14395, oil filter AM125424, fuel filter AM116304, spark plug M78543, every one of them on a 50-hour interval. What that guide does not contain is a carburetor, an ignition coil or a rewind starter; it stops at the service schedule. So the rule holds exactly where the money is. For a filter or a plug the hood badge is enough and Deere has done the cross-referencing for you. The moment the repair goes past routine maintenance, the guide runs out and you are back to the engine’s own number.

One more cell is closer to useful than it looks. Husqvarna is the only maker here that publishes the displacement in cubic inches — 32.9 for the TS 142, where everyone else prints cc — and cubic inches is the unit Briggs’ first two digits encode. It is not the model number, and it will not order a part. But it is the one spec on any of these pages that can be laid directly against a model number to check you are looking at the right engine family before you pay for anything.

That is not an oversight — a spec sheet sells a machine and the engine number identifies a service part. But it is the reason this question gets asked at all. This page said until September 8, 2026 that unless the engine and the machine came from the same company the number is not in the specification block, and the Ariens row above is the counter-example: two different companies, and the engine’s model number printed on the machine’s own page anyway. What holds is the weaker and more useful version — it is not reliable, so it is not something to count on before you walk outside. Where a machine maker does publish it, it may be in the specification block as Ariens does it, or filed somewhere a person shopping for a mower has no reason to look, as Deere does it. The copy you can always reach is stamped on the engine, and you have to go outside and read it.

There is a second supplier column that could have been added and was left out only for space: John Deere and Cub Cadet both name Tuff Torq hydrostatic transaxles on the machines above. Even the gearbox is somebody else’s.

Two brands where this advice inverts

Toro’s snowblowers and Ariens’ snowblowers carry engines the machine makers brand themselves — “Toro Premium,” “Ariens AX.” There is no engine manufacturer to look up, no independent parts catalog, no second service manual.

That cuts both ways, and honestly it cuts in the owner’s favor more often than not. You lose the ability to cross-shop an OEM carburetor against the engine maker’s own catalog. You gain a single, unambiguous parts channel: the machine’s model and serial number is the only lookup, and it is the correct one. For a snowblower repair that usually means fewer wrong parts, not more.

Which makes the exact form of that number worth getting right, because Ariens publishes two of them. The Deluxe 30’s page shows Model #921071 at the top and carries 92107100 in the page data underneath — the same six digits with two zeros appended, and the pattern holds across the series (921069 / 92106900, 921072 / 92107200). Ariens’ own guide to confirming a part fits labels the field its parts search expects a “6-digit model number”, which is the same six-digit rule the identification page sets out. Use the number printed on the machine’s data plate and on the page heading; the padded form is not what the lookup is asking for.

With one caveat that applies to the house brands more than to anyone else: with no engine manufacturer publishing a second, independent spec, the machine page is the only figure there is, and it is not always internally consistent. Ariens’ Classic 24 page listed the engine as 212 cc in one field and “AX 208CC” in another when it was read on August 28, 2026, and gave its throughput as both 58 tons/hour in the spec block and “up to 59” in the sales copy — which is why that page gets read on the model number, not the marketing copy. Take the value from the specification block for your exact model, and if two fields disagree, the parts catalog is the tiebreaker.

The rule, then, is narrower than “always use the engine number.” It is: find out whether your engine has an independent manufacturer. If it does, use its number. If it is a house brand, use the machine’s. Checking takes about four seconds once you are standing at the machine.

The companies changed names, and the search terms changed with them

Three ownership events in the last six years moved where the manuals and parts catalogs live. If you are searching an engine brand and getting a dead site or a redirect, this is why.

Kohler Engines is now Rehlko. Kohler Energy became a standalone business under Platinum Equity in May 2024 and rebranded as Rehlko on September 17, 2024. The engines still say KOHLER on the shroud. The website does not — kohlerengines.com now redirects to engines.rehlko.com. Anything written before late 2024, which is most of what ranks for Kohler engine questions, points at the old address.

That redirect is the front of a bigger gap, and it is where the advice above inverts. This page’s whole argument is that the engine is a second company with a second catalog — so identify it and go there. For a Kohler engine there is no longer anywhere to go: engines.rehlko.com/service-support/parts returns 404, and what replaced the parts route is a dealer locator with no consumer price on it. The catalog that does carry Kohler part numbers belongs to the machine maker. Of the 33,237 URLs in Cub Cadet’s sitemap on September 8, 2026, 993 are part pages with a KH- prefix: Kohler part numbers the mower company sells under its own SKUs. All 993 were read on September 8, 2026: 823 publish a price and 755 are priced and in stock, from $1.61 to $2,317.22 with a median of $13.84 — a catalog that runs from an O-ring to a complete shortblock, kept by the mower company for the engine company’s parts. The oil filter for the CV and CH engines this page’s Cub Cadet row runs on, Kohler 12 050 01-S, is $22.55 and in stock — priced by the mower company, not by the engine company whose name is on the part. So for Kohler the instruction this page gives has to be read backwards: the engine’s number is still what you need, and the place to spend it is the machine maker’s catalog.

Briggs & Stratton is owned by KPS Capital Partners. The company filed Chapter 11 in 2020; the bankruptcy court approved the sale on September 15 and Briggs announced its completion on September 23, 2020. The brand, the model numbering system and the parts catalog all survived intact, which is why the decoder above — Briggs calls it the chart for its “post 1965 model numbers” — still reads a current engine.

Cub Cadet and Troy-Bilt belong to Stanley Black & Decker. It bought the remaining 80% of MTD Holdings for $1.6 billion, completing on December 1, 2021. Same machines, same parts sites, different parent. It is worth knowing mainly because it is a reminder that two nameplates on the same store shelf can share an owner as well as an engine supplier — how far that goes is a question for its own page.

Honda, which looks like an orphan story and isn’t

Honda stopped building gas lawn mowers at its Swepsonville, North Carolina plant at the end of September 2023, and said so plainly — the line was converted to ATV production.

The obvious inference is that a Honda mower is now an orphan. It is not the right inference. Honda kept its GX and GCV engine business, kept its US parts and service operation, and in January 2026 restarted mower production at the same Swepsonville plant with the battery-powered ProZision line. A GCV170 is still a current-catalog engine.

Whether any five-year-old mower is worth a $200 parts bill is a separate question, and it is the one this site is mostly about. But “the manufacturer left” is not the reason to write one off.

Go and read it

The number is stamped into metal, not printed on a sticker, so it does not wear off. On a Briggs-powered push mower, Briggs lists three places to look: directly above the spark plug, on a plate between the valve cover and the air filter, or on the sheet metal above the muffler, either side. Kohler and Rehlko engines carry model, spec and serial together on a decal on the blower housing or engine cover.

Two cautions worth the sentence. Briggs warns that the numbers on the engine’s emissions label are commonly mistaken for the Model, Type and Code — they are not the same numbers and will not return your parts. And if a plastic shroud covers the stamping, that is a job for the machine’s manual or a servicing dealer, not for guesswork with the engine warm.

Write down all three numbers — Model, Type, Code — and photograph the plate. That photograph answers every parts question you will ever have about this machine, and it is the one preparation that shortens every call that follows, starting with the quote. The machine’s own plate is a separate errand with its own hiding places, and you want both.

Now that you have the engine numbers

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