GENERAL DESCRIPTION
The crankcase
is made
from high-grade
aluminium.
It is mounted
on
a rigid
aluminium
base rvhich
forms the oil
sump. In the
base
is
fltted
a
trough into
which the
dippcr on
the end of the
connecting rod dips at
each revolution.
This
trough is
kept at
constant level
by
oil
bein[ fed
through metering
holes
which connect to
the
main
sump.
The
crankshaft is
made of high quality
steel, and is
carried
on
taper
roller
or
ball bearings of large
dimensions.
The
crankshaft and
connecting-
rod assembly
are
very carefully
balanced.
The
connecting-rod is
stcel
with a phosphor
bronze small-end
bush. The
big-end is split and
fitted
with
white metal steel
backed shells.
The piston
is of die
cast aluminium
alloy.
It is fitted
with compression
rings,
one o{
rvhich is a
special
taper chrome-plated
ring and
must be
fitted
in
the
top
groove
with the fåce
marl<ed TOf
uppelmost, and an
oil
scraper rirq
above
the
gudgeon pin.
Drain holes åie
drilled in the
bottom ring groove
The
gudgeon
pin
is located
by
a circlip at
each end and ls {ully floating
in
the
gudgeon
bosses.
The
cylinder is
madc
from
close
grained
cast iron and
is provided
with
circumferr:ntial
fins of
special
shape for
cooling.
The cylinder
head
is made
from an aluminium
alloy,
deeply {rnned
to
assist
cooling.
It is
detachable and
fitted
with a
§asket-wirich
forms
thc
joint
betrveen
the
cylinder ancl head.
The
camshait
is
made
from meehanite
alloy,
and is driven
by heavy
spur
gears.
'lhe
pinion
is rnachined
from steel
and meshes
with
the camshaft.
The inlet
and
exhaust,cams
operate
directly on
the tappets.
Tappet
adjustment
is effected
by
the fitting of
difierent
thicknå§s
discs uiråer
tappet
heads.
fhc
whole of
the cam gear
is encloscrl
and running
in oil.
Lubrication is
by
JAI'
pa.tcuted
dipper
system
and is
entirely automatic
and
-very
eihcient,
_affording
ample
supply to all
working
parts.
'fhe
crankcase is- provided
with the
well-known
]AP
vacurrru
System
and
crankcase release,
ensuring a
clean
engine and
economy in oil.
The
th.rottle
is operated
by a centrifuga,l governor.
A
hand operated
choke,is
fitted
to
facilitate
starting
when engine is
cold.
A
centrifugal governor
is driven
by a spur wheel
meshing
with
the
cam-
shlft and. operates.the
throttle by
simple
mechanism.
A slow running
and
starting
lever is
fitted,
which is operated
against
the governor
arrn.
Peen 2
The flywheel
Ian
is of
cast
iron
and
is fitted
directly
on
the
cranksheft.
The
cooling
air is
supplied
by this
fan,
which
creates a
draught
over tho
cylinder head
and
portions of the cylinder, which are
correctly
flnned
for
this
purpose.
These
fins should be kept clean for efficient cooling.
The
cowl is designed
to
give
a cooling
draught to
the
necessary portiont
of
the cylinder and cylinder
head.
The
oil filler cap on the side
of the crankcase is
of
the
screwed
type.
Attached
is a
dipstick,
having high level mark.
THE DIPSTICK
tsOTTOM END INDICATES
DANGER LEVEL.
ALWAYS
XNBP MOVE THE
CAP
WHEN THE
ENGINE
IS RUNNING.
The engine base
must
be
standing
level
when checking or re-filling
oil.
A carburetter has been
specially designed for each engine. The setting
of
the
jets
should not
be interfered
with except by an experienced engineer.
It
is correctly
set
at the works,
and any slight alteration may upset the
smooth running
of the
engine.
Jets,
fi,lters,
etc.,
may
occasionally require cleaning to remove dirt
or
water.
This
can
be simply
done by blowing
air
through them. See
pages
22 to 25
for
maintenance
and
carburetter
parts list.
The damper on the
governor arm is
to
prevent hunting
by
putting extra
friction on the spindle. Great
care, however, must be exercised in adjust-
ing
this,
as
too
much friction will
prevent
the throttle
opening
fully.
lVhen commerclal
petrol
ls used,
lt le
advlsable
to
add
one table-
§poon of eng,lne otl wlth
one
gallon
of fuel. Thta should be well
mlxed.
COLD
§TARTING.
(")
Open
petrol filter tap by
turning in anti-clockwise direction.
Each filter
is
fitted
with a tap
which
requires to be screwed
either
fully
in for
OFF,
or
fully
out for ON, to ensure
leak
proof
operation.
(å)
Slip
the slow
running lever into
position
to
partly
close the throttle.
(r)
Push the carburetter
air choke levcr to close choke
for cold
starting
only.
Turn
engine slowly until compression is felt.
When
compression
is felt,
give
the starting
handle a
sharp
pull in
wpwørds
direction.
IMPORTANT.-Always
pull
starting
handle up smartly to start;
do not attempt
to start
by
continuous turniag.
When engine
has
started
release the slow running
lever.
When
engine commencss
to
pick
up speed,
puli
the Carburetter air
choke lever forward to
open choke.
HOT STARTING.
To facilitate restarting
a hot
engine
a release tap has been
provided
on the
inlet pipe. When starting difficulty
occurs, open the tap
and rotate
the
crankshaft
slowly
a
few
times to clear the induction system
of
excessively
rich
mixture. During this operation the
throttle should be left wide open.
The air
choke
should be
left
open
at all times for starting
hot
engines. With
the
tap still open, crank engine
to start in the usual
manner. A{ter engine
has
started and
is running evenly, close the tap to
prevent
weakening of
the
mixture.
(d)
(r)
U)
(g)
Pecn 3
To Next Page
Loading...
General