In 1952 the hallowed halls of the Vincent-HRD
Owners Club were trembling with anticipation.
The Stevenage factory had intimated that a new
model was about to be announced to the motor
cycling press. Prospective purchasers waited
impatiently, cheque books at the ready. Prospective
record-breakers postponed their attempts with
their current machines.
In 1953 the same hallowed halls were trembling
with shock. The manufacturers of The World's
Fastest Standard motorcycle - This is a Fact,
not a Slogan! had announced a clip-on engine
of 45cc - the Firefly! Indignation filled the
pages of MPH, the esteemed journal of the VOC.
It is certain that, if a Firefly owner attempted
to join the Club in 1953, he would have received
a very frosty welcome indeed!
Nowadays, a Firefly is regarded as a most desirable
asset amongst the Vincent fraternity. Epics
such as the efforts of Team Firefly in the 1991
FIM Rally in Eindhoven have added their own
little bit of glory to the marque. But how did
the Firefly come about?
For many years, Phil Vincent had had a very
good relationship with Miller, the electrical
people. Hence, while most other motor cyclist's
batteries were kept happy with the superb Lucas
AVC unit, the Vincenteer's battery either boiled
with rage or faded through lack of nourishment
with the Miller cartridge trying to supply its
needs. Be that as it may, in 1952 the motor
cycling press announced a new clip-on engine:
the Miller Firefly. A road test and technical
description appeared but the exact date and
in which of the two main British motor cycle
magazines eludes me for the moment [It was The
Motor Cycle on 31/1/1952 and there was also
a photograph of the Brussels Show model in the
previous week's edition - Ed]. The machine seemed
much the same as the Firefly that went into
production, except that the sliding back of
the engine to engage the rear wheel was accomplished
by a lever below the saddle on the left hand
side of the cycle. For some reason Miller didn't
continue with the production run; this passed
to Vincent Engineers instead.
The engine unit went on sale in 1953. The only
significant change was that the rear wheel engagement
was effected by a handlebar lever, rather like
a clutch lever in reverse. Pull in to engage.
A ratchet holds the lever in. Release the ratchet
to disengage. The only other handlebar control
to the engine is the combined decompressor and
throttle lever. Forward shuts the throttle and
opens the decompressor; back shuts the decompressor
and opens the throttle. The engine fits on rails
under the bottom bracket of the cycle and slides
back to engage the rear wheel with a toothed
roller. This location gives a nice low centre
of gravity and does not upset the trim of the
cycle. The long thin tank fits to the down tube
of the cycle frame.
There are a few interesting technical features.
The engine unit has to be very slim to fit where
it does but a spacer is normally used to make
the gap between the pedals about an inch wider.
There is only one size of bearing; this is part
number VF41 and is a ball bearing of dimensions
3/4″ × 1 5/8″ × 5/16″.
The RHP number is KLNJ3/4 but the equivalent
by any other manufacturer of bearings will suffice.
An alternator is fitted; surely one of the first
cyclemotor units to be so equipped; the vast
majority of larger motor cycles in 1953 still
relied on dynamo and DC electrics. Ignition
is by a coil fitted in a recess at the base
of the fuel tank.
Few problems were experienced with the engine
unit. The only major one that I know of concerned
the rear drive roller, part number VF131AS.
The outer toothed rim is rubber bonded to the
inner sleeve. The bonding was prone to failure
on some early models but this was quickly rectified.
The only problem that I have with my Firefly
is a reluctance to start on petroil from cold
but a few squirts of lighter fuel down the carb
does the trick!
Production life of the Firefly was only three
years. In 1953 only the engine unit was available;
in 1954 and 1955 it came fitted in a specially
designed Sun cycle. [The complete machine was
known as the Vincent Power Cycle. Sun frames
were used at first, later ones were made by
Phillips. - Ed] In 1955 Vincent Engineers ceased
production of their big motor cycles, although
they continued for some more years with industrial
engines, Amanda water scooters and the like.
Demise of the Firefly, however, is usually blamed
on the NSU Quickly.
It is widely known that a liaison between Vincent
and NSU led to the ill-fated NSU-Vincent Fox
production run. What is not generally realised
is that Vincent took on the marketing of the
Quickly in the UK. This they did at the expense
of the Firefly and to their own eventual cost,
as they were so successful at selling the little
German machine that NSU decided to cash in on
it and handle sales of the Quickly themselves