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Lauson outboards were manufactured by the Hart Carter Corporation in New Holstein Wisconsin from the 1940's through the mid 1950's. They had long been a manufacturer of engines and other machinery, mostly for farm use. Lauson outboards were billed as the "Cadillac" of outboards for fisherman and sported a number of innovative features, the most unique being that all of their outboards utilized 4-cycle engines. The advantages of 4-cycle engines are high fuel economy and excellent slow speed operation compared to contemporary 2-strokes.

Hart Carter sold out to the Power Products (Tecumseh) Company in the mid 1950's and they did not elect to continue outboard production.

1951 Lauson S-351 3hp

S-350/351 Owners Manual pdf

Year & Model:
1951 Lauson S-351
Horsepower: 3

Bore: 2.125"
Stroke: 1.75"
Ignition: Wico Magneto
Point Gap: .020
Cooling: Forced air-cooled

Condition: Restored
Retail price when new: $129.50
Weight: 48 lbs.
Oil/Gas Mix: None! 4-Cycle
Spark Plug: Champion J-8


See Below



1951 Lauson S-351 3hp

Above is my restored 1951 Lauson S-351 3hp outboard - it took the remains of three to put this motor back together. It is a single cylinder 4-stroke with the valves "in-block" and is air cooled by a force draft down from the fins on the side of the flywheel. The block is cast iron with the crankcase, leg and other parts made of aluminum. It is a heavy motor for 3hp weighing in at the equivalent of motors with twice its horsepower. The magneto is fixed and throttle is by the small side draft Tillotson carburetor. Crankcase oil is filled and checked on the port side of the motor, the engine is even equipped with a mini oil pump for the crank ends, connecting rods and valve cam! The motor is equipped with handy features like an easily adjustable knob for the co-pilot (tiller friction) and a little compartment in the tiller to store shear pins.

The S-351 starts relatively easily, often requiring 3 or 4 pulls when cold and one or two when warm. It idles superbly and is reasonably quiet and smooth up to the mid-range. The top end is another story... the whir of machinery and vibration become quite unpleasant. Fuel economy is excellent at the low and mid range but I couldn't stand running the motor long enough at top end to make an accurate assessment of its economy. Power, in my estimation, is close to the rated 3hp.

I am in the process of restoring a T-651 6hp twin. It is basically two of the 3hp engines combined in a fore & aft opposed twin configuration. The twin is not as "clean" a design as the single and is assembled in a manner Rube Goldberg (ace bodger) would appreciate! After 4 years of working on the twin the last part I need is the front engine cowl - hopefully a picture of it completed will be seen here soon.

Someone asked the location of the ID Tag - it is in the photo below. (Same location on the T-651)

About Lauson 4-Stroke Outboards

In the early 1940's and just after WWII Lauson produced the OB-410 a small single cylinder 2.5hp outboard. Starting in 1948 Lauson single and twin cylinder 4-stroke outboards have a model I.D. tag below the power head on the transom saddle. The serial numbers break down roughly as follows:


S-300 = 1948-9
S-350 = 1950
S-351 = 1951
S-352 = 1952
S-353 = 1954 to 1956

T-600 = 1948-9
T-6 50 = 1950
T-651 = 1951
T-652 = 1952
T-653 = 1954 to 1956

R = Gearshift

All of the 300 and 600 series motors were of 4-stroke design, a good SAE 30 or SAE 40 motor oil should be used in the crankcase. The On/Off knob on the front of the engine kills the spark and also closes the crankcase breather so the engine can be transported without losing oil. Despite Lauson's best efforts, small oil leaks at the bottom seal and power head base are common- so I keep a drip pan under the engine when it is stored.

Ignition is by Wico magneto with a point gap of .020, engine timing is fixed. A number of people have experienced coil failure due to the engine overheating- see below.

Carburetor is a simple Tillotson located on the starboard rear corner. Throttle is achieved by the carburetor alone from the top lever on the front of the motor. (the bottom lever actuates the choke) Fuel is a good grade of regular gas.

The engine is cooled by air forced by fan blades on the flywheel and directed over the cooling fins on the cylinder. To properly cool the lower engine cover must be in place - this is often missing on these old motors. When the lower cover ( front + back on the twin) is missing not enough of the forced air passes over the cooling fins causing the engine to overheat. Prolonged usage is thought to overheat the coils and cause them to fail, evidence of melted coil insulation is often cited.

They are great running little motors and idle very well and are quiet up to the mid-range. Top speed can be a little noisy. About the only down sides to the Lauson's are their weight and the fact that parts are very hard to come by.

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