Kawasaki FR691V

Kawasaki FR691VThe Kawasaki FR691V is a 0.73 l (726 cc, 44.3 cu-in) V-twin 90° air-cooled 4-stroke internal combustion small gasoline engine with vertical shaft, manufactured by Kawasaki Heavy Industries LTd., for general-purpose applications, such as residential zero-turn mowers, lawn and garden tractors.

The FR691V has 90 degrees V-twin design with vertical PTO shaft, overhead valves, cast iron cylinder liners, spherical combustion chamber and rotating metal grass chopper screen. The engine is equipped with the electronic spark ignition system and internally vented carburetor with fuel shut-off solenoid. The motor uses a high-performance lubrication system and single-stage air filter.

The engine has an automatic compression release (ACR) system with bendix type starter. 13A or 20A charge coils are available as an option.

It has a 78.0 mm (3.07 in) cylinder bore and 76.0 mm (2.99 in) piston stroke. Compression ratio rating is 8.2:1. The Kawasaki FR691V produced 20.9 PS (15.4 kW; 20.6 HP) at 3,600 rpm or 23.4 PS (17.2 kW; 23.0 HP) at 3,600 rpm of maximum horsepower and 53.7 Nm (5.5 kg·m; 39.6 ft·lb) at 2,000 rpm or 53.6 Nm (5.5 kg·m; 39.6 ft·lb) at 2,000 rpm of torque.

General information

Engine Specifications
ModelFR691V
Type4-stroke, OHV, V-twin 90°
Displacement726 cm 3 (44.3 cu-in)
Max. horsepower 20.9 PS (15.4 KW; 20.6 HP) at 3,600 rpm
23.4 PS (17.2 KW; 23.0 HP) at 3,600 rpm
Max. torque (crank PTO) 53.7 Nm (5.5 kg·m; 39.6 ft·lb) at 2,000 rpm
53.6 Nm (5.5 kg·m; 39.6 ft·lb) at 2,000 rpm
CarburetorInternally vented with fuel shut-off solenoid
Cooling systemAir-cooling
Ignition systemElectronic spark ignition
Lubricating systemFull pressure with spin-on oil filter
Starting systemBendix type starter
Charging system13A or 20A charge coil (option)
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel consumption245 g/HPh
Cooling systemPressurized forced circulation type

Dimensions and Weight

Kawasaki FR691V
Length, mm (in)501 (19.7)
Width, mm (in)466 (18.3)
Height, mm (in)392 (15.4)
Dry weight, kg (lb)40.0 (88.2)

Tightening torque specs

Tightening torque specs
Cylinder head46 Nm; 4.6 kg·m; 33.9 ft·lb
Connecting rod10 Nm; 1.0 kg·m; 7.4 ft·lb
Flywheel56 Nm; 5.7 kg·m; 41.3 ft·lb
Crankcase cover27.5 Nm; 2.75 kg·m; 20.3 ft·lb
Intake manifold9 Nm; 0.9 kg·m; 6.6 ft·lb
Oil drain plug7 Nm; 0.7 kg·m; 5.2 ft·lb
Valve clearance lock nut11 Nm; 1.1 kg·m; 8.1 ft·lb

Maintenance data

Engine
Maximum speed3500 ± 100 rpm
Idle speed1500 ± 100 rpm
Cylinder compression4.5 kg/cm2 (64 psi) at 500 rpm
Valve clearance
Intake valve0.10-0.15 mm (0.004-0.006 in)
Exhaust valve0.10-0.15 mm (0.004-0.006 in)
Oil system
Oil type4-stroke or an equivalent (SJ or higher class)
Recommended oilSAE 10W-40, 10W-30
Oil capacity (with filter changed) With oil filter: 1.7 litre
Without oil filter: 1.5 litre
Ignition system
Spark plugNGK: BPR4ES
Spark plug gap0.7-0.8 mm (0.027-0.031 in)
Ignition coil air gap0.2-0.4 mm (0.008-0.011 in)
Spark plug tightening torque22 Nm; 2.2 kg·m; 16.2 ft·lb
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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25 Comments

    • The Kawasaki manual state’s to use 10W-30 if the outside temperature is 14F to 90F. Use 10W-40 if the outside temperature is 14F to over 104F. I use 10W- 40 since the temperature here in the south in the summer is usually hot and humid. Check your Kawasaki manual if you have one.

  1. I need a shroud for my 691v part number 59066-xxxx. How do I know which one my engine uses? It’s on a cub cadet mower.

  2. If I change to canister air cleaner, swap manifold and carb for double… I lose 1hp … Why? Why does the fx691v have 22hp and the fr691v has 23hp… If I change to bigger carb and more air… I lose HP? Please explain.

    • Could be a couple of reasons. Compression ratio, camshaft specs, etc.
      OR it could just be where they decided to dyno the engine at. You can find the dynograph of the FR691V. There’s the 23HP Kawi 691v and the 25/26hp Kohler. The Kohler makes 2 more ft-lbs of torque but at 2600RPM while the Kawi makes 40 ft-lbs of torque at 2200RPM.
      The Kohler has something like a 3.3″ bore and 2.7″ stroke while the Kawi has a (roughly) 3″ bore x 3″ stroke.

      Now, assuming you have the same block, bore, stroke, the difference could be the RPM where the measurement is given or there could be some upgrades done to the heads/cam.

      It’s why I’d take, and did take, the Kawi FR691v over that Kholer KT745. The Kawisaki is designed more like a working engine. It’s got a square borexstroke. It makes peak torque quite a bit lower in the RPM range and is only short by 2 ft-lbs. It’s like the old 300 I6 vs 302 V8 debate, but it ain’t that serious.

      • And maybe your horsepower measurement is at the exact same RPM. If so, then yeah, going with a bigger carb and more air is going to move your peak power up higher in the RPM range, so you need to know that it’s running at that higher RPM to take advantage of your set up.

        It’s like taking any engine and opening up the exhaust and intake. They tend to lose a little down low. These engines are rated @ 3600RPM.. and that’s probably where the default throttle “max” position puts them. But you know good and well they’ll do 5000RPM if you rev ’em… not that you’d want to mow that way. Waste of fuel and it wouldn’t be making as much power up there. I’ve seen the dynograph of the Kawi FR691V. It’s only a couple of ft-lbs shy of max torque at 1200RPM. It’s got that excellent power curve from the larger stroke.. among other things, but yea. It makes power all through the throttle range. Of course, you aren’t going to get it to do that without fiddling around to put a heavy load and full throttle and hold it at 1200RPM. I’m just saying, on the engine dyno, it shows the torque and horsepower curves. It’s exactly what you’d want to see in a 460 Ford haha.

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