Decode a EXi / 550EX-725EX Series Stamp
In production: c. 2015-present (EXi trim with Just Check & Add launched mid-2010s; the underlying 140/150/163cc OHV platform and its operator-manual series predate the EXi badge - the manual covering model series 80000/90000/093J00/100000 is the platform reference, and illustrated parts lists for current stamps such as 103M02 were still being revised in 2020).
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Where the stamp is
On these engines the model-type-code is most often stamped into the metal on the left side of the overhead valve (OHV) cover. Briggs & Stratton's official model-number guide also lists, depending on type: stamped into the metal near the spark plug, on a metal tag above the rewind starter, on a label on the fuel tank, and on a tag riveted to the blower housing. Record all three lines exactly as stamped - model, type and code - before ordering parts. It is stamped into the metal, not printed on a sticker - wipe the area clean and read it at an angle if it is faint.
Worked example
A real stamp from this family: 104M02 0196-F1
| Part | Value | Means |
|---|---|---|
| Model | 104M02 | The six-character model stamp. The first two characters are the displacement class in the Briggs numerical designation system (10 = the ~10 cu in class; this engine's actual swept volume is 163cc). The remaining characters encode the basic design series and the crankshaft orientation / PTO / starter configuration group. On modern stamps some positions are letters (here M) - the letter is part of the model exactly as stamped and must be copied character for character. |
| Type (first four digits) | 0196 | The type pins down the exact build: for 0196-F1 the manufacturer documents 163cc, 7.25 gross torque, a 25 mm x 3-5/32 in crankshaft drilled and tapped 3/8-24 with a 1/4 in keyway, ReadyStart, and a 3,200 rpm maximum. The sibling type 0197-F1 is the same engine with a 7/8 in shaft instead of 25 mm - which is why a model number alone can never spec a repower. |
| Type suffix | F1 | The letter-number suffix completes the type: it marks the trim/assembly revision level of that type. A different suffix can mean a different carburetor, tank or control set on the same four-digit type. |
| Code | Code (third stamped line, format YYMMDD + assembly suffix) | The code is the build stamp: its first six digits are the build date in year-month-day order, followed by digits/letters identifying the assembly plant and line. The code is what a dealer uses to apply date-sensitive parts changes, so quote it when a parts list splits by code. (No individual engine's real code is published here - codes are unique to each engine and must be read off the stamp.) |
Reading the type
Types are where this family actually lives. A single model stamp such as 09P702 or 104M02 covers dozens of types that differ in crankshaft diameter (7/8 in vs 25 mm), crankshaft length (1-13/16, 2-7/16, 3-5/32 in and 62 mm all occur), blade-brake clutch vs plain shaft, recoil vs electric vs InStart starting, governed speed (2,800-3,200 rpm) and EXi vs non-EXi oil systems. Suffixes matter too: -F1 is the common current suffix, while -H5 types are European-market builds that often carry the shorter 62 mm shaft. When two sources disagree about a shaft or a capacity, they are usually describing two different types of the same model - resolve by type, not by averaging. Service parts, by contrast, are remarkably stable across the family: the operator manual for the whole platform lists one paper air filter (593260), one foam filter option (799579), and spark plugs 692051 (140/150cc) or 594056 (163cc).
The model-number rules
Reading the model number
- Digits 1-2Displacement (cu in)
- Next digit/letterBasic design series
- Next digit/letterCrankshaft orientation: 0-4 or A-G horizontal, 5-9 or H-Z vertical
From the Briggs & Stratton model number key.
PTO bearing / drive digit
| 0 | Plain bearing |
| 3 | Ball bearing |
| 4 | Ball bearing, pressure lubrication |
| 5 | Plain bearing, gear reduction (6 to 1), CCW rotation |
| 6 | Ball bearing, gear reduction (2 to 1), CCW rotation |
| 7 | Plain bearing, pressure lubrication |
| 9 | Plain bearing, auxiliary drive |
Starter digit (last)
| 0 | Without starter |
| 2 | Rewind (recoil) starter |
| 5 | Electric starter |
| 6 | Alternator only |
| 7 | Electric starter with alternator |
The code: build date
The code's first six digits are the build date, read YYMMDD - two-digit year, month, day. The trailing characters are the assembly plant and line. A code gives a build date, not a sale date or the year of the equipment it powers.
EXi / 550EX-725EX Series engines in the database
- Spec records for this family are being verified.
Quick answers
Does an EXi engine really never need an oil change?
That is what the manual says for Just Check & Add models: 'an oil change is not required' - you check the level before use and add oil as needed. It does not mean maintenance-free: the capacity is only 15 oz, so running low does real damage quickly, and non-EXi types in this family (most 550EX/500E builds) still follow a normal oil-change schedule in the same manual.
How much oil does a 550EX / 625EXi / 725EXi hold?
15 oz (0.44 L) per the operator manual, across all three displacements. Some Briggs & Stratton store listings for replacement engines say 16 oz; the manual figure is the one to fill to, using the dipstick as the final check. Oil is SAE 30 detergent oil (API SF/SG/SH/SJ or higher) in normal temperatures.
Why does my 725EXi have a different spark plug gap than my old 550EX?
Because the manual specs them differently: the 163cc series (100000) is gapped at 0.030 in, while the 140cc (90000) and 150cc (093J00) series use 0.020 in. Valve clearances are the same across all three: 0.004-0.008 in on both valves.
550EX, 625EXi, 675EXi, 725EXi - are these different engines?
They are trim/tune levels on three shared platforms, not four separate engines. 550EX is the 140cc platform, 625EX/625EXi the 150cc, and 675EXi/725EXi are two torque tunes (6.75 and 7.25 ft-lb) of the same 163cc platform - the 675EXi and 725EXi even share crankshafts, gaskets and service parts. The model stamp and type, not the trim badge, identify what you have.
Where do I find the model number on an EXi engine?
Start at the valve cover: on most of these engines the full model-type-code is stamped into the left side of the metal OHV cover. If it is not there, check near the spark plug, the metal tag above the rewind starter, the fuel tank label and the blower housing tag - Briggs & Stratton lists all of these as stamp locations for this engine class.
Can I repower my mower with a different EXi model?
Usually yes within the family - the mounting footprint is shared - but only if the crankshaft diameter and length match your old engine's type exactly. This family was built with 7/8 in and 25 mm shafts in at least four lengths, and the trim name tells you none of that. Match the full model-type from the stamp, or measure the shaft (diameter and length from the mounting face) before ordering.