Restore   Chapter 25   1955 Hummer ←  Up  →     

1955 Hummer


"Heretofore, Harley-Davidson models have been designated by letters and by piston displacement in cubic inches or cubic centimeters. In bringing out this new model, it was decided to give it a name. [...] The more we use this name, the better we like it. We hope you, too, will like it", says the February 1955 Dealer News Bulletin.

Serious students of H-D history might argue that the 1919 W - Sport Model really deserves the distinction of being the first model with a name, but the Hummer was the first model to have its name proudly displayed on the gas tank.

The Harley Hummer is named after Dean Hummer. Why? Read more about Dean and the story of the Hummer on our History page.

The Hummer has no speedometer. No front brake. A squeeze-bulb horn. A magneto powers both the spark plug and the lights, hence there is no battery. There's no fork panel behind the headlight. If you're guessing that this is an economy model, you're absolutely correct.

Motor - General

The Hummer's 125cc "B" engine cases were completely redesigned to accommodate the Bendix magneto. While many parts were re-used from the Model 125 and Model 165, there are numerous internal differences.

Motor - Cylinder - Piston

The cylinder now has the flange for bolt-on mounting of the carburator. The piston and pin from the Model 125 are used.

Flywheels - Shafts - Connecting Rods

The flywheels and plates are the same as the Model 165, but the magneto shaft changed. The connecting rod and crank pin are the same as the Model 165.

Crankcases and Fittings

The crankcases, primary cover, and magneto cover are very different.

Carburetor and Air Cleaner

A Tillotson MT-43A carburetor replaced the L&L carb previously used. The carburetor covers used on the Model 165 disappeared. The fuel line is now rubber, and the fuel valve changed to a hose barb on the bottom instead of a screw-on connection. A new-style air cleaner to fit the Tillitson carburetor was available as an option.
See the Carburetors and Air Cleaners chapter for details.


The magneto replaced the Model 125/165 generator. It has has two output coils. The "Lighting Coil" provides power to the headlight and taillight. The "spark coil" provides power directly to the spark plug - no external coil is used. There is one set of contact points, and these are different from the Model 125/165 points.


Not applicable to this model.

Spark Coil and Spark Plugs

The external spark coil was eliminated, since it is now a part of the magneto.

Starter and Transmission

A new kickstart lever debuted in 1955 on the Hummer and Model 165s. The differences are subtle. The Hummer did not have the rubber cover on the lever.
The transmission is mostly unchanged, with the exception of the countershaft gear and some small parts.
The gear Shifter Lever received a new rubber-less stud on the Hummer. This stud (34618-55) is much longer than the Model 165's rubber-covered stud.
See the Kickstart Levers chapter for details.

Clutch and Clutch Control

The clutch sprocket now has 33 teeth instead of 31 teeth (TLB) on the Model 165. Some small clutch parts changed.

Chain and Sprocket

Primary: The front chain is unchanged. The motor sprocket has 12 teeth - it is the same as used on the Model 125 (40195-47). The clutch sprocket (37707-55) has 33 teeth (noted above) (SPC55). Main drive: The rear chain (4000-47) is the same as used on the Model 125. The transmission sprocket (35201-47) is unchanged (SPC55) with 14 teeth (SER66). The rear hub sprocket (41476-52A) is the same as used on the Model 125, with 43 teeth. (SPC55)

Rear Wheel and Brake

The rear hub shell assembly and sprocket changed due to different gearing on the Hummer. The rear axle changed slightly. The brake assembly remained the same.

Rims and Spokes

Tire size changed to 3.50 x 18 inch. Rims on Hummers were painted black. The spokes were 1" shorter. Almost all advertising pictures of the 1955 Hummer show Firestone Sportsman tires.
See the Wheels and Tires chapter for details.

Front Wheel and Brake

The front wheel hub shell changed since the Hummer did not have a front brake. The bearings and some small parts changed also.

Front Brake Control

There's no front brake lever, because there's no front brake.

Front Fork

The tab in the right slider to hold the brake backing plate was removed. The right slider is peculiar to 1955-1956 Hummers. The Fork Upper Plate has the work "Hummer" in it, as well as having holes for the headlight dimmer switch. A Fork Upper Plate Cover covers the speedometer hole. The speedometer was an accessory. The Fork Panel was removed.
See the Front Forks chapter for details.
See the Fork Panels chapter for details.

Frame and Rear Fork

The frame for the Hummer is all new. The bosses on the front downtube for the external coil mount was removed. The footpeg mounting shaft is now an integral part of the cross-tube. There is no need for the mounting tabs for an electric horn, or for the now optional toolbox. A "U"-shaped mounting bracket is needed to mount toolbox.
See the Frames chapter for details.

Safety Guard and Splash Shields

Jiffy Stand and Footrests


Not applicable to this model.


The Hummer saddle (52001-55) "covering is black, waterproof, long-wearing Vinyl plastic" (TLB)

Dual Seat and Trail Seat

Not applicable to this model.

Buddy Seat

(Accessory) - No changes.

Luggage Carrier

(Accessory) - No changes.


The Hummer handlebars do not have the holes for the horn or headlight switch.


(Accessory) - The windhsield reverted to the 1948-1951 S configuration. A number of the brackets had changed for the 1952 S and 1953 and later ST.

Fenders and Chain Guards

The chainguard is new, although it is very similar to the Model 125 chain guard. The difference is that it uses a threaded stud (like the Model 165s) instead of the square nut (like the Model 125s) at the rear mounting. The gear indicator arm is not used on any Hummer or 1960s models, so the painted numbers on the chainguard are useless.
See the Chainguards chapter for details.

Gas Tank

The gas tank is the same size and shape as the Model 165, but there is no "tunnel" through the tank for the key-switch and wiring, since the key-switch was not used. The filler cap remains on the right side of the tank. The fuel valve is similar to the Model 165, except that the bottom connection is a hose-barb, and connects to the carburator via a rubber hose.
See the Gas Tanks chapter for details.

Tool Box

The Hummer did not have a tool box. An accessory kit "Toolbox and fittings with tools" (64200-55) was available which included a "U-shaped" bracket (64371-55) to mount on the lower frame rail, since the toolbox mount had been removed from the Hummer frame. The kit included other nuts, bolts and spacers.

Muffler and Exhaust Pipe

The Hummer exhaust pipe is painted with a silicone high-temp silver paint, unlike the Model 165 pipe which was chrome plated. The muffler has not changed - it still has the hanger welded to the muffler. The upper clamp has one rib, the lower clamp has two ribs.

Battery and Holders

The battery and battery box were removed.

Speedometer and Drive

The Hummer did not come stock with a speedometer, and as noted under Forks above, a Fork Cover Plate was used. A conversion kit (Part # 67009-55) was offered as an accessory to retrofit the speedometer on 1955-1966 Hummers. The conversion kit included the 67000-51B speedometer which was used on 1954-1956 Model 165s.
See the Speedometers chapter for details.

Headlamp and Tail Lamp

The headlight did not change, but the headlight switch moved from the tank to the left rear side of the Upper Fork Plate. The tail lamp changed from the bullet style to the round style. The tail lamp has a double-contact connector and bulb, even though there is no brake light switch or wiring.

Front Fender Lamp and Parts


The Hummer horn is a bicycle-style squeeze-bulb unit mounted on the handlebar. These are marked "Yoder Mfg. Co. Los Angeles" and "Made in U.S.A." These are extremely rare.


The wiring harness is quite different than the Model 125/165. Commercially available "Hummer" wiring harnesses may be more like the 1958-1959 Hummer models which have a speedometer and brake light.


The keyswitch in the gas tank was removed. The ignition function became a "kill button" in the engine's magneto cover. The light function moved from the gas tank to the left rear side of the Upper Fork Plate. The light-switch has a knurled knob, and only controls the lights - low-beam, off, high-beam. The knurled knob is difficult to find.


The ammeter was not available for Hummer and 1960's models.

Voltage Regulator

The voltage regulator was removed.

Auxiliary Seat and Footrests

(Accessory) - Not available for the Hummer.

Saddle Bags



Miscellaneous Common Items

Accessories - Not in Parts Catalogs

Paint Colors

Standard: Atomic Blue, Pepper Red
Optional Colors: None

See the Paint Colors chapter for details.


Atomic Blue

Pepper Red

  Last updated: May 09, 2011 ←  Up  →