Restoration of a Neptune 1.7 hp "Mighty Mite" Outboard

If these little motors could talk, imagine the stories they could tell, just lay back on a sunny day, close your eyes, let your mind wonder a bit.  Kind of makes you want to take an old flat-bottomed rowboat with one of these on the stern, put on a old pair of jeans, a straw hat with a spear of grass in the corner of your mouth then just do a lazy day on the lake trying to drown a worm.   In the years they were made, they provided lots of unhurried recreation at a modest cost.

These little motors were normally found in either a 1.2, 1.5 or 1.7hp, (same basic motor), but the 1.7 used a larger piston and different head.  The hp increased as the years/models advanced.   They were made by Muncie Gearworks (Muncie Transmissions for all you Chevy fans) and were basically unchanged from about 1938 to 1974.  Only weighing in at 17 lbs, they were great for 8' or 9' prams.  They were nicknamed by a few as "Egg Beaters". 

I won't go into the history of these little motors to much, but will provide a link to what someone smarter than I and has been in the business longer, has already put it together  CLICK HERE.   And for a link to another website that covers all the year/models from 1930 to 1991, price they sold for and carburetors/specifications, CLICK HERE.

Briefly, the company started in Muncie Indiana in 1910, by 2 brothers who were associated with Warner Gear Division of Borg Warner.  They got into the outboard motor business in 1930 building a 2hp opposed twin, then in 1938 they copied the popular single cylinder 1.2 hp Evinrude Scout motor.

Their outboard motor production ceased during both WWII and the Korean conflict because of government contracts for war components.

Unfortunately, Neptune pissed-off their dealer organization back in about 1950 by offering to sell direct to the public.  Sales plummeted as dealers dropped the brand, and Muncie Gears Works shut-down production of Neptunes for about 4 years.  They then began selling Neptune the 1.7 hp motors under the Mighty Mite name about 1955 but only by mail order through advertisements in the likes of Life magazine, Boys Life, Popular Mechanics etc.  Word was that you could earn a Mighty Mite by selling a specified number of subscriptions to magazines.

The business moved and sold a couple of times with the last in 1978 but production slowed and it appears to not have seen production after that date until it folded about 1990.

Price in the mid 1950s was $79.50.

Mechanical Description ;  The 1.2 and 1.5hp had the spark plug protruding to the RH side of the head as witnessed by the bulge in the side cowling of the LH header photo above.  The 1.7hp had the spark plug relocated at the center rear of the head.  The early model numbers seem to have incorporated the years into the model code.  After 1952 or so then the model numbers was different.

These motors were single cylinder water cooled motors.  The water pump impeller was a close fitting aluminum centrifugal pump.  No thermostat was used.  The ignition was magneto type using points and condenser made by R. E. Phelon of East Longmeadow MA.  Carburetors were Tillotson of a couple different versions depending on vintage.  There was no neutral or shifting and steering was approx. 270 degrees.  All of the early motors were bare sides, but the some of the late motors used a cast aluminum side panels.  All but the real late motors used a wrap around rope on top of the flywheel to start the motor with.  There was no choke, but a "tickler" on the top of the carburetor to slightly flood the motor with fuel.  The carburetor used a inverted main jet attached to a cork bowl float.

The fuel tanks appear to hold 2 pints which had a run time full tank 1 hr. 20 minutes.  They were made in about 3 different shapes, with the teardrop being the most popular.  Later tanks were bobbed off at the rear allowing for the motor to be stored laying on this part of the tank.

Restoration Project ;  A goodly number of years ago a friend offered me some of his deceased father-in-law's old junker outboard motors.  Of the lot I picked was 3 of these little jewels.  One was seized up, another had a broken clamp bracket that had been welded of sorts, the other's exhaust pipe had badly bent and beat up.  All in all, for this project, I picked out the what appeared to be the newest, most easily repairable one for this project, being a model AA1 then cannibalized parts off the seized motor, which then made it somewhat complete for this restoration project.  However it did have the broken skeg.  These motors had sat for in a garage for probably over 25 years.

I first removed the flywheel, removed the points, flushed the timing plate off with lacquer thinner filed the points removing any oxidation, reassembled everything on the timing plate.   The coil looked OK, but how to tell if the condenser would function.  I reassembled the flywheel, held onto the spark plug wire and cranked it over.  NO SPARK.  So back to the drawing board.

After doing some web surfing I found Doug Penn appears to have bought out the remains of the manufacturer some years after they finally shut the door.   Also on his website, he shows on a video how to test both the coil and condenser of older OMC outboards.  CLICK HERE for a coil testing video, and HERE for a condenser testing video.   I figured that these magneto parts were basically the same as the OMC parts he was lecturing on, so checked out the coil using his method which it then proved fine.  Not possessing the equipment to test the condenser, I just inspected the wiring, found that the condenser wire was standing high enough to rub the flywheel magnets.  Re-routing this wire solved that problem.   It now shocked me if I held onto the plug wire when cranking the motor over, so spark appeared OK.  But it would not fire off.

In talking to an experienced motorcycle mechanic that was well accustomed to seeing older magneto type ignition bikes, he related that (1) most condensers are replaced simply because the cost is low as compared to labor for trouble shooting the electronics later if it doesn't run.  (2) His method of telling if a condenser is bad, is look at the points, if they are pitted badly, it is because of a failing condenser.  However if the points look evenly worn, just clean them with lacquer thinner, drag non-waxed paper like a brown paper bag thru the contacts a few times, adjust them and 99.9% of the time it will run great.

AA-1 Magneto plate  

OK, do what I should have done first off, check the compression.  Only got 40#, after 3 pulls, which I doubt was enough to make this little single cylinder motor run.  I pulled the head, tipped the motor up so the cylinder was upright, and with the piston up above the port holes, poured in 1/2" of Seafoam.   After a day it had all soaked down past the rings.  A clean up of any oil in the cylinder then a strip of 100 grit emery cloth rubbed rotationally inside the cylinder walls with the piston bottomed out did a cheap hone job.  The compression was then raised to 70# after 2 pulls, which I thought was quite respectable. 

Inspecting the fuel tank revealed some rust inside.  I then poured about a 1/2 a pint of gasoline along 2 handfulls of abrasive triangle tumbling stones inside, tightened the cap and began shaking when ever I got near the tank for 2 or 3 days.  This got out most of any loose rust that I figured would ultimately loosen up.  

Almost ready, but this time I used a spark tester set at  just over 3/16", when cranked over it light up like a Christmas tree.  Choking it by tickling the carburetor along with using a bit of starting fluid sprayed in the carburetor throat, it popped on 3rd pull, started on 4th pull.  Now to adjust the carburetor settings.

One point of interest, if you are used to newer twist grip throttles found on most other motors, you assume that the throttle/timing plate moves right handed.  However with these motors that do not use a twist throttle, the timing plate increases the speed as it is moved to the LEFT.  To start these motors, you need to position the timing plate knob slightly beyond center and to the left otherwise you may be cranking for a while.

In the photo on the left below shows this restoration motor right after I got it running but before any cosmetic work being done other than replace the welded transom mounting clamp and a 1/2" aluminum rod for a tiller handle.

Before, right after it was running  After
This may take a while as the house needs painting

I have not been inside the gearbox yet and since this motor has a broken skeg, when I do, I will make a new skeg out of 1/8" aluminum sheet, copying one of the other originals then heliarc weld it onto the gearbox.  The reason is, that the one I would cannibalize is broken in a worse area to repair plus I may want to restore the other somewhat complete motor at some later date.

It is hard to get good real life photos of these motors because of the abuse they have suffered over the years.  It appears that some of the tank colors may have been different depending on the models and years.

For a pdf exploded view of the WC-1 & AA-1A motors CLICK HERE

Statistics ;  For the 1.7 hp motors
Cylinder diameter 1.562"
Stroke 1.500"
Bearings,   bronze bushings, both mains & rod
High speed jet, one turn out.
Idle jet 1/2 to 3/4 turn out.
Fuel mix is 16:1
Point gap is .020
Plug gap .025, Champion J6C or J8J plug.
Tillotson carburetor #AJ-21A on the model AA1
Flywheel key  .125" X .200" X 1.00"
Motor is primed by depressing the float pin where it sticks out of the top of carburetor float chamber (sometimes referred to as a "Tickler".

From what information I can piece together the following is close to the year/model for this style of the single cylinder motors which later became known as the "Mighty Mite".  There were others made prior to this date, but they were of a different style or twin cylinder motors.  You may notice some collation between the model numbers and the year of manufacture up until  1942 during WWII, then a carry over in 1946 with the models again resuming this in 1947.  Then there was a carry over of model numbers into years some later years.  From 1948 on was a different story.    I have not been able to track down any serial numbers however.

1936-37       OB-11, 12,
1938            2A38            
1939            2A39, 10A2
1940            10A1, 10A2, 11B2
1941            10A2, 11A2
, 11B2
1946            11A2, 11B2, 14B2
1947            17A1, 17B1, 17B2

1948-55       A1, A2, AA1, AA2, B1
1956            AA1
1957            AA1-A
1961-69      WC-1
1970            500
1978            700
1980-86       800, 800B, Mighty Mite III

It seems that on a motor model that the 2nd letter being another letter (as AA-1) possibly designates a deluxe version, in this case probably was supplied with side cowlings.  I know of one motor that has an X as a last model number.  No idea of what that means.

The original recommended fuel mix at the time these motors were made was 16-1 as the bearings are just bronze instead of the newer roller type.
Using new full synthetic oil you should be able to get by quite well with 24-1 or possibly 32-1, which will also prolong the spark plug life.

In the photo below this particular motor has had the shaft shortened considerable, apparent to fit in a more compact display.

Here is a fully restored 1947 AA1 mounted in a display  

Recommendations ;   At the end of your running these motors, it is a good idea to turn off the gas and run the carburetor bowl empty prior to pulling the motor out of the water.  Also make sure the screws are tight on the handle and all around the engine.  If not, they will vibrate loose, ending up in the water.  Pack the gearbox with marine wheel bearing grease.   It may also be a good idea to put rubber or nylon washers on the gas tank mounts to ease vibrations to the tank. This motor tends to crack the gas tanks.

Observances ;  I have a feeling that many of these motors if supplied with the side covers, after a while the owners discarded the covers, as it appears they were hard to keep tightened. And the motors ran just as well without them.     

Carburetor kits #3345 available from
The Carburetor Shop LLC
204 East 15th Street
Eldon, Missouri 65026

Decals available from @ $34.50 a set
American Outboard Motors & Salvage
12611 Ocean Gateway
Cordova MD 21625

Hard core parts for some of these outboards are getting more difficult to find as time goes on. Many older outboards used common Ignition and Carburetor venders for that period. Discount Marine Parts has Ignition and Carburetor repair kits for most all of these older outboards. If we don't have what your looking for, we have many sources to locate your part. Obviously some parts are just not available. We can sometimes find it used and often we have the part made if there is enough demand. Discount Marine Parts has a large inventory of parts for most brands of American made Outboards, Inboards and Sterndrives. We also have most parts and service manuals available.


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Originated 03-02-2011, Last updated 12-15-2014 
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