Kawasaki FR691V Vs. FS691V Engines: What's The Difference Between Them?
If you're looking into replacing your riding lawn mower's engine, you might've come across both the FR691V and FS691V engines from Kawasaki. As the names would suggest, these are very similar engines, and it's easier to tell you what the pair have in common versus what's different. They are both big 23 HP mower engines with similar architecture, but two particular details separate the pair.
The FR691V is a smaller motor with dimensions of 18.85" x 18.18" x 22.24" compared to the larger dimensions of 19.68" x 18.30" x 15.39" for the FS691V. As a tradeoff for the larger size, the FS691V boasts a dual-element air filtration system, a step up from the FR691V's single-stage air filter. Outside of those two points, the motors have the same horsepower, starter, and fuel delivery system. Of the two, the FS line of engines is bigger and stronger, but that doesn't mean that you'd be upset if you picked up an FR motor. Both are two-cylinder engines with the same 726 cc displacement.
How different are the FR691V and FS691V engines?
With both motors having the same horsepower, it's easy to make the assumption they perform similarly. While that's true, Kawasaki positions the FR line as something a homeowner would gravitate toward while the FS series is made for medium-sized commercial jobs. That doesn't mean you won't be able to use both of them at home, but if you're using the mower for a prolonged amount of time covering a wide area, you can benefit from the FS691V's better air filter.
To be clear, neither engine is something you'll put into the little self-propelled mower you're using in your backyard. Instead, these are for the commercial mowers you see roaming around a city block, apartment complex, or a house in a rural area. If that sounds like a job you have to tackle, these motors should be on your radar, but they don't come cheap.
Finding a mower with one of these engines is easily done, but you'll need to be prepared to spend a few thousand dollars. Cub Cabet, a trusted lawn mower brand, has a riding mower with the Kawasaki FR691V engine that costs $3599 at Home Depot. It's certainly overkill for a basic yard in a city, but if you're nice enough to mow your whole street's grass you might find it worth its value.