1903–1929 Harley-Davidson Models | Early Era Singles, Twins & JD Reference

This Early Era Harley-Davidson Model Reference covers Harley-Davidson motorcycles built from 1903 through 1929, including the earliest single-cylinder machines, the first V-twins, F-head engines, horizontally opposed twins, late-1920s singles, JD models, and the first flathead V-twins. It is built as a year-by-year lookup page for restorers, collectors, and readers using the Harley VIN Decoder or the broader Model Reference 1903–1969.

The early years do not follow the same clean engine-number and model-code logic used in later Harley-Davidson production, so this page keeps the reference structure simple: each production year is grouped with its listed primary models, other models, racing models, new features, paint or color notes, and model/VIN notes where those details appear in the source. For later prewar machines, continue to the 1930–1936 V-Series page, where Harley-Davidson model coding becomes more standardized.

Use the navigation below to jump directly to a production year, move between the Riding Vintage era pages, or open the VIN and model-reference resources that support Harley-Davidson identification work across the site.

Quick Navigation

Years:
1903 | 1904 | 1905 | 1906 | 1907 | 1908 | 1909 | 1910 | 1911 | 1912 | 1913 | 1914 | 1915 | 1916 | 1917 | 1918 | 1919 | 1920 | 1921 | 1922 | 1923 | 1924 | 1925 | 1926 | 1927 | 1928 | 1929

Resources:
Harley VIN Decoder | Model Reference 1903–1969

Understanding Model Listings

This page is organized by production year. Each year section lists the primary Harley-Davidson models for that year, then separates other models, racing models, new features, paint or color notes, and model or serial-number notes where those details appear in the source. In the earliest years, Harley-Davidson naming is much less standardized than it becomes later, so the listings are presented in a normalized year-by-year format to make the full early era easier to read and compare.

Example: JD — F-head V-Twin — 74 cu. in

JD = model designation
F-head V-Twin = engine family and cylinder layout
74 cu. in = engine displacement

Early Harley-Davidson engine numbers were not standardized in the same way as later VIN systems, and sales-model descriptions do not always map neatly to a single stamped serial format. That is why the listings below work best when paired with the Harley VIN Decoder and the broader Model Reference 1903–1969.

Era 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 early flathead designs. Model naming, equipment distinctions, and serial-number structure evolved substantially across these years, which makes year-by-year reference especially important. By the late 1920s, the model lineup begins pointing toward the more recognizable structures that appear in the 1930–1936 V-Series era.

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. To place decoded machines within the full range of production, use the Harley-Davidson Model Reference 1903–1969.

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.

For later Harley-Davidson model development and more standardized VIN and paint systems, continue to the 1930–1936 V-Series era.

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.