The Motor Company supplies many American police forces with their motorcycle fleets. Harleys are especially noted for the tradition of heavy customization that gave rise to the chopper-style of motorcycle.
The classic Harley-Davidson
engines are two-cylinder, V-twin
engines with the pistons mounted
in a 45° "V". The crankshaft has
a single pin, and both pistons
are connected to this pin
through their connecting rods.
This design causes the pistons
to fire at uneven intervals, the
consequence of an engineering
trade-off to create a large,
powerful engine in a small
space. This design choice is
entirely vestigial from an
engineering standpoint, but has
been sustained because of the
strong connection between the
distinctive sound and the
Harley-Davidson brand. This
design, which is covered under
several United States patents,
gives the Harley-Davidson V-twin
its unique choppy
"potato-potato" sound. To
simplify the engine and reduce
costs, the V-twin ignition was
designed to operate with a
single set of points and no
distributor, which is known as a
dual fire ignition system,
causing both spark plugs to fire
regardless of which cylinder was
on its compression stroke, with
the other spark plug firing on
its cylinder's exhaust stroke,
effectively "wasting a spark."
The exhaust note is basically a
throaty growling sound with some
popping.
-
Sportster
With the
exception of
the
street-going
XR1000 of
the 1980s,
all
Sportsters
made for
street use
have the
prefix XL in
their model
designation.
For the
Sportster
Evolution
engines used
since the
mid 1980s,
there have
been two
sizes of
Sportster
Evolution
engine.
Motorcycles
with the
smaller
engine are
designated
XL883, while
those with
the larger
engine were
initially
designated
XL1100. When
the size of
the larger
engine was
increased
from 1,100
cc to 1,200
cc, the
designation
was changed
from XL1100
to XL1200.
Subsequent
letters in
the
designation
refer to
model
variations
within the
sportster
range, eg.
the XL883C
refers to an
883 cc
Sportster
with cruiser
or custom
styling,
while the
XL1200S
designates
the
now-discontinued
1200
Sportster
Sport.
- Dyna
models
utilize the
big-twin
engine (F),
small-diameter
telescopic
forks
similar to
those used
on the
Sportster
(X), and the
Dyna chassis
(D).
Therefore,
all Dyna
models have
designations
that begin
with FXD, eg.
FXDWG (Wide
Glide) and
FXDL (Low
Rider).
- Softail
models
utilize the
big-twin
engine (F)
and the
Softail
chassis
(ST).
- Softail models that use small-diameter telescopic forks similar to those used on the Sportster (X) have designations that begin with FXST, eg. FXSTB (Night Train), FXSTD (Deuce) and FXSTS (Standard).
- Softail models that use large-diameter telescopic forks similar to those used on the touring bikes (L) have designations beginning with FLST, e.g. FLSTF (Fat Boy) and FLSTC (Heritage Softail Classic).
- Softail models that use Springer forks with a 21-inch wheel have designations that begin with FXSTS eg. FXSTS (Springer Softail) and FXSTSB (Bad Boy).
- Softail
models
that use
Springer
forks
with a
16-inch
wheel
have
designations
that
begin
with
FLSTS
eg.FLSTSC
(Springer
Classic)
- Touring
models use
Big-Twin
engines and
large-diameter
telescopic
forks. All
Touring
designations
begin with
the letters
FL, eg. FLHR
(Road King)
and FLTR
(Road Glide)
- Revolution
models
utilize the
Revolution
engine (VR),
and the
street
versions are
designated
Street
Custom (SC).
After the
VRSC- prefix
common to
all street
Revolution
bikes, the
next letter
denotes the
model,
either A
(base
V-Rod), B
(discontinued),
D (Night
Rod), R
(Street
Rod), SE
(CVO Special
Edition), or
X. Further
differentiation
within
models are
made with an
additional
letter, e.g.
VRSCDX
denotes the
Night Rod
Special.
- The factory drag bike, the VRXSE Destroyer, uses X instead of SC to denote a non-street bike and SE to denote a CVO Special Edition