performance
to suit a wide variety of
sporting events.
These arc
indicated in Table I.
Cams.
various cam combinations
are available for the
cold Star
engine, and the sele.tion of
these depend$
upon the
desir€d
performance,
They are
shown id Table
II,
and as a
general
rule the
pair
of cams
fitted to an etrgine
at the
factory during maNfacture and
special tuning, is
selected
as being the most suitable
for the specification
ordered
by the
prospective
owner.
Thus, if a low com-
pression pistor
is fitted, and
the machine is to be used for
touring, the cams in the first
line
will
be employed. The
reminader of the table
is devoted to competitive
events
where the highest
possible performance
is
required, and
for these
the
owtrer
is advised to follow the
recomrnen-
dations
exactly
as
given.
The main
jet
size for alcohol fuels depends
largety
upon the
actual fuel used, as there arc one
or two
pro-
pdetary
blands available at the
present
time in
addition
to
pule
methanol, and the composition
of these varies
somewhat. It is for this and other rcasons
that the figutes
given
for alcohol and dope are subject
to alteation,
If the machine has been ordered in
the first
place
with
the T.T. carbuetter specially tuned for
alcohol fuel it will
already have a
suitable
main
jet,
but if the owner is making
the
oonversion himself, he should take as a rough
guide
the
fact that
the main
jet
for alcohol fuel should be
at
least
two and a half times as big
as
that fot
petrol.
For certain
fuels, however, an even larger size may
be found necessary,
and the owner is advised to experiment
with this
point,
bearing in mind that a careful test of the mixturc strength
with rcspect to
perfomance
should be made
as
quickly
as
possible,
as full throttle work with a weak mixture is liable
to
cause rapid
seizurc.
It
is
advisable when using alcohol
fuel to run
with
the
mixture
slightly
on the rich side.
Any
published
recommendation
for a
given
fuel should, there.
fore, be looked upon ss a minimum. In
the case of the
832 for J.A.P. mcing fuel, No. 800 or
No. 850 should be
suitable, while for
pure
methanol ajet size
up to No. 1300
may be found
necessary.
For the B34
Gold Star the sizes
will, of
course,
be
propodionately
larger and
will
probably
be
up to 1700. The
throttle valve and needle
position
may
vary slightly to suit individual
cases.
Petrol Tånk. A two or
four
gallon
tank can
b€
fitted
if
speÆially ordered,
Ignition Timing. The best timing for the B32
ol! dope is
$
inch
advance,
and
fr
inch
advance on
petrol
or
petrol-
benzole,
39'(lå
inch)
Clubman's. On the B34 use
*
inch
advarce for dope and
+
inch
advance for
petrol
or
pehol-
benzole
({d
inch
for
sc@mbles
with
engine
prefix
No.
BB),
36'
(l*
inch Scrambles
and Clubman's).
Vålve Timing. Tiniing
procedure
is as described for
other
'B'models.
(See page
46.) Theactualvalvetimingfor
Gold
Stars
differs
frcm Standard
'B'
models,
but the
pinioN
are
malked
in
the same way as the standard
pinions
to
facililate assembly.
In addition, the
idet ard exhaust
pinions
are
marked
'IN'
and
'EX'
respectively.
TABLE I
PISTONS
.
These Pistons
are for engines
number with
prefix
CB
832 Gold Star
B34 Gold Star
Component
No.
Complete
Com.
Ratio
Component
No.
Complet€
Com.
Ratio
65.1681
6.5
65-1245 6.8
*65-1921
7.25
*65-1930
't.25
65-t265
65-1616
8.0 65-1285
8.0
*65-2254
r65-2260
8.5
65-1614
*65-2287
9.0
65-1532
.
*65-2300
9.0
65-1687 13.1
65-1279 1t.0
52
and after
englne
53
l
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