1903–1929 Harley-Davidson Early Era Models

1903–1929 Harley-Davidson models including single-cylinder, F-head, early V-twins, and flathead machines with specs, variations, and history.

Explore Other Eras: 1903–1929 Early Era | 1930–1936 V-Series | 1936–1947 Knucklehead | 1948–1965 Panhead

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Overview

The Early Era represents Harley-Davidson’s foundational years, beginning with single-cylinder machines and progressing through the introduction of V-twins, F-head engines, horizontally opposed twins, and the first flathead twins. Model naming, equipment distinctions, and serial-number structure evolved dramatically across these years, which makes year-by-year reference especially important.

VIN Information

Early Harley-Davidson engine numbers were not standardized in the same way as later VIN systems. From 1903 through 1915, the model system is primarily numeric. Beginning in 1916, year-based identification with lettered model designations becomes more recognizable. For this reference, the source data has been normalized into year-first lines so it reads consistently with the later-era pages and the VIN decoder. Primary Models on this page are V-twins and later twin families, while singles and horizontally opposed twins are grouped under Other Models. For complete engine number decoding, see the Harley-Davidson VIN decoder and serial number guide.

1903 Harley-Davidson Models

Primary Models

First Bike — F-head Single — 24.74 cu. in

New Features

Loop frame
Larger-than-usual engine

Paint / Colors

Black paint finish

Model / VIN Notes

1903 is the starting point for Harley-Davidson production in the source file.
This first machine is treated as a single-cylinder design rather than part of a broader production family.

1904 Harley-Davidson Models

Primary Models

Model 0 — F-head Single — 24.74 cu. in

Paint / Colors

Black paint finish

Model / VIN Notes

1904 continues the earliest single-cylinder pattern.
The source still reflects a very simple early production structure with no later-style VIN logic.

1905 Harley-Davidson Models

Primary Models

Model 1 — F-head Single — 24.74 cu. in

Paint / Colors

Black paint finish

Model / VIN Notes

1905 remains within the very early single-cylinder model sequence.

1906 Harley-Davidson Models

Primary Models

Model 2 — F-head Single — 26.8 cu. in

New Features

Increased displacement

Paint / Colors

Black paint
Renault Gray optional

Model / VIN Notes

1906 increases displacement relative to the earliest machines.
The paint listing also begins to show optional finish variation.

1907 Harley-Davidson Models

Primary Models

Model 3 — F-head Single — 26.8 cu. in

New Features

“Sager” sprung fork

Paint / Colors

Renault Gray
Black optional

Model / VIN Notes

1907 introduces the “Sager” sprung fork in the source notes.
The finish options also invert the previous black-first pattern.

1908 Harley-Davidson Models

Primary Models

Model 4 — F-head Single — 26.8 cu. in

Paint / Colors

Renault Gray
Black optional

Model / VIN Notes

1908 continues the single-cylinder format with the same displacement shown in 1907.

1909 Harley-Davidson Models

Primary Models

5-D — V-Twin — 49.48 cu. in

Other Models

5-A — Single — 30.16 cu. in
5-B — Single — 30.16 cu. in
5-C — Single — 30.16 cu. in

Model / VIN Notes

1909 is the first year in the source to show a Harley-Davidson V-twin.
The single-cylinder family continues alongside it.

1910 Harley-Davidson Models

Primary Models

No Primary Models listed for 1910

Other Models

6-A — Single — 30.16 cu. in
6-B — Single — 30.16 cu. in
6-C — Single — 30.16 cu. in

Racing Models

6-E — Racing Model

Model / VIN Notes

1910 is notable in the source for including an explicit racing model entry.

1911 Harley-Davidson Models

Primary Models

7-D — V-Twin — 49.48 cu. in

Other Models

7-A — Single — 30.16 cu. in
7-B — Single — 30.16 cu. in
7-C — Single — 30.16 cu. in

New Features

Mechanical inlet valves

Model / VIN Notes

1911 introduces mechanical inlet valves in the source notes.
This is an important technical milestone in the early Harley engine story.

1912 Harley-Davidson Models

Primary Models

8-D — V-Twin — 49.48 cu. in
X-8D — V-Twin — 49.48 cu. in
X-8E — V-Twin — 61 cu. in

Other Models

8-A — Single — 30.16 cu. in
X-8 — Single — 30.16 cu. in
X-8A — Single — 30.16 cu. in

Model / VIN Notes

1912 expands the V-twin family and introduces the 61 cubic inch X-8E in the source set.

1913 Harley-Davidson Models

Primary Models

9-E — V-Twin — 61 cu. in
9-F — V-Twin — 61 cu. in
9-G — V-Twin — 61 cu. in

Other Models

9-A — Single — 35 cu. in
9-B — Single — 35 cu. in

Model / VIN Notes

1913 shows a broader 61-cubic-inch V-twin lineup with multiple lettered variants.
The single family also grows to 35 cubic inches.

1914 Harley-Davidson Models

Primary Models

10-E — V-Twin — 61 cu. in
10-F — V-Twin — 61 cu. in
10-G — V-Twin — 61 cu. in

Other Models

10-A — Single — 35 cu. in
10-B — Single — 35 cu. in
10-C — Single — 35 cu. in

Model / VIN Notes

1914 continues the established 61-cubic-inch V-twin pattern with multiple single-cylinder companions.

1915 Harley-Davidson Models

Primary Models

11-E — V-Twin — 61 cu. in
11-F — V-Twin — 61 cu. in
11-G — V-Twin — 61 cu. in
11-H — V-Twin — 61 cu. in
11-J — V-Twin — 61 cu. in

Other Models

11-B — Single — 35 cu. in
11-C — Single — 35 cu. in

Racing Models

11-K
11-KR
11-KT
11-KRH
11-KTH
11-K12
11-K12H

Model / VIN Notes

1915 is one of the richest early years in the source, with multiple V-twin variants and a large racing-model group.
It is also the last year before the source shifts into the later year-plus-letter identification style.

1916 Harley-Davidson Models

Primary Models

E — F-head V-Twin — 61 cu. in
F — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in

Other Models

B — F-head Single — 35 cu. in
C — F-head Single — 35 cu. in

Model / VIN Notes

1916 marks the beginning of the later year-based lettered designation system in the source.

1917 Harley-Davidson Models

Primary Models

No Primary Models listed for 1917

Other Models

B — F-head Single — 35 cu. in
C — F-head Single — 35 cu. in

Model / VIN Notes

1917 is sparse in the source and lists only the B and C singles.

1918 Harley-Davidson Models

Primary Models

E — F-head V-Twin — 61 cu. in
F — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in

Other Models

B — F-head Single — 35 cu. in
C — F-head Single — 35 cu. in

Model / VIN Notes

1918 returns to the familiar E / F / J V-twin grouping.

1919 Harley-Davidson Models

Primary Models

F — F-head V-Twin — 61 cu. in
FS — F-head V-Twin — 61 cu. in
FUS — F-head V-Twin — 61 cu. in (Govt. use only)
J — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in

Other Models

W — Horizontally opposed flathead twin — 35.64 cu. in

Model / VIN Notes

1919 introduces the W family of horizontally opposed twins in the source.
This year also shows sidecar and government-use suffix variation within the F-head V-twin family.

1920 Harley-Davidson Models

Primary Models

F — F-head V-Twin — 61 cu. in
FS — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in

Other Models

W — Horizontally opposed twin — 35.64 cu. in
WF — Horizontally opposed twin — 35.64 cu. in
WJ — Horizontally opposed twin — 35.64 cu. in

Model / VIN Notes

1920 continues the 61-cubic-inch F-head families and expands the horizontally opposed twin lineup.

1921 Harley-Davidson Models

Primary Models

F — F-head V-Twin — 61 cu. in
FS — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in
FD — F-head V-Twin — 74 cu. in
FDS — F-head V-Twin — 74 cu. in
JD — F-head V-Twin — 74 cu. in
JDS — F-head V-Twin — 74 cu. in

Other Models

CD — F-head Single — 37 cu. in
W — Horizontally opposed twin — 35.64 cu. in
WF — Horizontally opposed twin — 35.64 cu. in
WJ — Horizontally opposed twin — 35.64 cu. in

Model / VIN Notes

1921 is a major expansion year because the 74-cubic-inch FD / JD families appear alongside the 61-cubic-inch twins.

1922 Harley-Davidson Models

Primary Models

F — F-head V-Twin — 61 cu. in
FS — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in
FD — F-head V-Twin — 74 cu. in
FDS — F-head V-Twin — 74 cu. in
JD — F-head V-Twin — 74 cu. in
JDS — F-head V-Twin — 74 cu. in

Other Models

CD — F-head Single — 37 cu. in
W — Horizontally opposed twin — 35.64 cu. in
WF — Horizontally opposed twin — 35.64 cu. in
WJ — Horizontally opposed twin — 35.64 cu. in

Model / VIN Notes

1922 largely carries forward the expanded twin structure established in 1921.

1923 Harley-Davidson Models

Primary Models

F — F-head V-Twin — 61 cu. in
FS — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in
FD — F-head V-Twin — 74 cu. in
FDS — F-head V-Twin — 74 cu. in
JD — F-head V-Twin — 74 cu. in
JDS — F-head V-Twin — 74 cu. in
JDCA — F-head V-Twin — 74 cu. in
JDSCA — F-head V-Twin — 74 cu. in

Other Models

W — Horizontally opposed twin — 35.64 cu. in
WF — Horizontally opposed twin — 35.64 cu. in
WJ — Horizontally opposed twin — 35.64 cu. in

Model / VIN Notes

1923 adds further 74-cubic-inch variation within the JD family.

1924 Harley-Davidson Models

Primary Models

F — F-head V-Twin — 61 cu. in
FE — F-head V-Twin — 61 cu. in
FES — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in
JE — F-head V-Twin — 61 cu. in
JES — F-head V-Twin — 61 cu. in
FD — F-head V-Twin — 74 cu. in
FDCB — F-head V-Twin — 74 cu. in
FDSBS — F-head V-Twin — 74 cu. in
JD — F-head V-Twin — 74 cu. in
JDCB — F-head V-Twin — 74 cu. in
JDCBS — F-head V-Twin — 74 cu. in

Model / VIN Notes

1924 introduces one of the most complex combinations of 61- and 74-cubic-inch F-head model suffixes in the early-era source set.

1925 Harley-Davidson Models

Primary Models

F — F-head V-Twin — 61 cu. in
FE — F-head V-Twin — 61 cu. in
FES — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in
JE — F-head V-Twin — 61 cu. in
JES — F-head V-Twin — 61 cu. in
FD — F-head V-Twin — 74 cu. in
FDCB — F-head V-Twin — 74 cu. in
FDSBS — F-head V-Twin — 74 cu. in
JD — F-head V-Twin — 74 cu. in
JDCB — F-head V-Twin — 74 cu. in
JDCBS — F-head V-Twin — 74 cu. in

Model / VIN Notes

1925 carries forward the same broad F-head V-twin structure shown in 1924.

1926 Harley-Davidson Models

Primary Models

F — F-head V-Twin — 61 cu. in
FE — F-head V-Twin — 61 cu. in
FES — F-head V-Twin — 61 cu. in
J — F-head V-Twin — 61 cu. in
JE — F-head V-Twin — 61 cu. in
JES — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in
FD — F-head V-Twin — 74 cu. in
FDCB — F-head V-Twin — 74 cu. in
FDSBS — F-head V-Twin — 74 cu. in
JD — F-head V-Twin — 74 cu. in
JDCB — F-head V-Twin — 74 cu. in
JDS — F-head V-Twin — 74 cu. in

Other Models

A — Flathead single — 21 cu. in
AA — OHV single — 21 cu. in
B — Flathead single — 21 cu. in
BA — OHV single — 21 cu. in

Model / VIN Notes

1926 adds a new single-cylinder family mix that includes both flathead and OHV single designations.

1927 Harley-Davidson Models

Primary Models

J — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in
F — F-head V-Twin — 61 cu. in
FK — F-head V-Twin — 61 cu. in
FS — F-head V-Twin — 61 cu. in
JD — F-head V-Twin — 74 cu. in
JDL — F-head V-Twin — 74 cu. in
JDS — F-head V-Twin — 74 cu. in
FD — F-head V-Twin — 74 cu. in
FDL — F-head V-Twin — 74 cu. in
FDS — F-head V-Twin — 74 cu. in

Other Models

A — Flathead single — 21 cu. in
AA — OHV single — 21 cu. in
AAE — OHV single — 21 cu. in
B — Flathead single — 21 cu. in
BB — Flathead single — 21 cu. in
BAE — OHV single — 21 cu. in

Model / VIN Notes

1927 further broadens the V-twin naming structure and introduces more late-1920s suffix complexity.

1928 Harley-Davidson Models

Primary Models

J — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in
JX — F-head V-Twin — 61 cu. in
JXL — F-head V-Twin — 61 cu. in
JH — F-head V-Twin — 61 cu. in
F — F-head V-Twin — 61 cu. in
FH — F-head V-Twin — 61 cu. in
FS — F-head V-Twin — 61 cu. in
JD — F-head V-Twin — 74 cu. in
JDH — F-head V-Twin — 74 cu. in (two-cam)
JDX — F-head V-Twin — 74 cu. in
JDXL — F-head V-Twin — 74 cu. in
JDS — F-head V-Twin — 74 cu. in
FD — F-head V-Twin — 74 cu. in
FDH — F-head V-Twin — 74 cu. in
FDS — F-head V-Twin — 74 cu. in

Other Models

A — Flathead single — 21 cu. in
AA — OHV single — 21 cu. in
AAE — OHV single — 21 cu. in
B — Flathead single — 21 cu. in
BA — OHV single — 21 cu. in
BAE — OHV single — 21 cu. in

Racing Models

JDH — two-cam racing-derived variant

Model / VIN Notes

1928 is one of the most model-dense years in the early-era file.
The two-cam JDH stands out as the clearest racing-derived model called out in the source.

1929 Harley-Davidson Models

Primary Models

D — Flathead V-Twin — 45 cu. in
DL — Flathead V-Twin — 45 cu. in
J — F-head V-Twin — 61 cu. in
JS — F-head V-Twin — 61 cu. in
JXL — F-head V-Twin — 61 cu. in
JH — F-head V-Twin — 61 cu. in
F — F-head V-Twin — 61 cu. in
FL — F-head V-Twin — 61 cu. in
FS — F-head V-Twin — 61 cu. in
JD — F-head V-Twin — 74 cu. in
JDH — F-head V-Twin — 74 cu. in (two-cam)
JDF — F-head V-Twin — 74 cu. in
JDXL — F-head V-Twin — 74 cu. in
JDS — F-head V-Twin — 74 cu. in
FD — F-head V-Twin — 74 cu. in
FDH — F-head V-Twin — 74 cu. in
FDL — F-head V-Twin — 74 cu. in
FDS — F-head V-Twin — 74 cu. in

Other Models

A — Flathead single — 21 cu. in
AA — OHV single — 21 cu. in
B — Flathead single — 21 cu. in
BA — Flathead / OHV single designation family — 21 cu. in
BAF — OHV single — 21 cu. in
C — Flathead single — 30.5 cu. in

Paint / Colors

Early standard finishes include Black and Renault Gray
Later years add Olive Green and Brewster Green
Two-tone options appear in the late 1920s

Racing Models

Racing entries visible in the source set include 10 6-E and the 1915 11-K series
Late-1920s racing-derived or competition-oriented variants include JDH and related high-performance twin models

Model / VIN Notes

1929 is the final year before the V-Series transition.
It combines mature F-head twin families with the appearance of the new 45-cubic-inch D / DL flathead V-twins.
The source-level paint summary also looks back across the early era rather than isolating just this single year.

Model Lifecycle Summary

Single-Cylinder Families

Early singles dominate 1903–1908.
Lettered single-cylinder families continue through the mid-1920s and diversify into both flathead and OHV forms by the late 1920s.

Early V-Twins

The first V-twin appears in 1909.
61-cubic-inch F-head V-twins become the backbone of the line in the 1910s and 1920s.

74-Cubic-Inch F-Head Family

The 74-cubic-inch FD / JD families appear in 1921 and become increasingly complex through the late 1920s.
Performance and racing-oriented variants become more visible late in the decade.

Horizontally Opposed Twins

The W family appears in 1919 and continues through the early 1920s.

Transition Toward the Next Era

The late 1920s show Harley-Davidson moving toward the more recognizable model structures that appear fully in the 1930 V-Series era.