BSA B31 - Clutch, Chain, and Brake Adjustments

,,,,
,.
I*ll:".Tqi"g.
rt
u-a rare
ffiilcc
ror-thc
masneto
'
.j
:
prnron
to
slacken
_98
gnd
df{ilcb
the igritiotr
seuins-
"ååd.d,ii,*",^gTm
l:
;:rmfl
,:"i
rr,.
.,'å"i?
It is,
however,
advisable
to
check
over
the
timing
after
c4rrymg
out-any
adjustment
ro the
magneto
cåntact
polDls,
as- a
sttght variarion
of the
points
tends
to advaDce
or
.retard
the
trming.
(Opening
the
points
advances
umtng,
ctostng
tåem
retards
!imiDg.)
t/
-I.f
lhe timing
requires
re-sefting,
first
che.k
that
fie
,,
ruuy-open
gap
at ttre
poiD6
iq
between
.Ol0 in.
aDd
.Ol2
in.
,
ln:l
re.gpÆ,ih9
rimins
q{er:
al,.d
in
S-doineTå[Eh
not.ro
dåyrlåEE
thesmall
frdløe
ff
fie riming
cover
which
reeos
olt_to
the hollow
crankshaft.
It
is advisable
to leave
:T",,b*.S
sqews
in
position
(half
unscrewed
aod
spaced
equa
y
rouod
tle
cover)
while
the
cover
joint
is
brokeD.
With
the
cove!
r€moved,
take
of
the
nut locking
the
111ETt9
pinign
on
!!s-shaft,_aod
with the
aid
of
a
maioeio
pln.lon
extractor
withdraw
tbe
pinion.
(Note:_The
Iatter
ts.altacned
-to
a.taprr€d
shafr
and
can
only
be releascd
wfin
salety
by ustng
the
proper
extraqor.)
.
To reset
the timing,
tum
the
eDgiae
forward
utrtil
the
pNlon
reaches
top
dead
centle
on
tlero/trpression
stroke.
Now
turb
the engine
bact
until
the
fi3(6f,
ha.
O".""na.J
ft
in.
(BjJ,
.
in.). This
operat
ion
is
siinptined
ir top
iåil!
engaged
aDd
the rear
wheel
tumed
backward.. (poi
Cofa
Star models
see.page
53.)
Turn
rhe
contacl
bleaker
in
irs
du€ctton
of_t^otalion
until
the
points
are
just
open
(not
more rban
.00.2
io.),_wiri_
the
ignition
tevir
in
ihe
fu
y
advanc€d
-positiotr.
Lightly
tap
rhe
rnagneto pinion
on
ro
tls snaltr
ltgh-ten
t]le
nut,
and
carefully
check
figures
and
posriions.
If setring
is
correct,
finally
tighre;
the
ma€nero
ptnlon
Dut.
t t is
ftost
impon4nt
that
the
ignil
ion
scttlng
is accurate.
Too
much
or
too ti le
advan;e
will
rcsult in.
highcr
running
temperaturcs
-a
auv
*ua"
ptslon
seizure. (See
also Magdyno
Fixing
page
tg.)
,/
('hrtch.
Thc
mflin
clurch
adjusrment
is totally
enclosed'
l|t thc
gcitrbox
r,Lrrcr
cover,
and is
exposed
when
the
6llcr
cnn rs r€nx)vc(|,
,
The
adjustitrg
scrcw
4
Fig. t t,
is locked
in
posirioo
by
tle
nut,{..
For
Comp. and
swingi-o8
arm modils
see
Fig,
13, /l
and
C respectively,
aod after
releasing
the latre;,
adJust
the screw
so that there
is
a little
clearance
between
the. ball
atrd
the
clutch
push
rod,
Then
re-tiShten
the
locknut
and replace
the filler
plug.
Fig.ll.
Clutch
and
lront
chain
adjustmenl
Fu
her
adjustment
is
prcvided
by the
knurled
thumb
nut
C
(-E
oncorb_p.
and
Swinging
ArD),
on
top of the
g€arbol
KememDer,
tlowever,
lbat
some
free
movement
itr
the
control
arm is
necessary,
as if rbe
adjustmen(
is too
close
ruere
wl
be
conslant
pressure
on the
clutch, with
con_
sequrnl
wear aqd
loss
ofefficiency, (For
Cold
Star RaciDg
see
Handlebar
levers, paSe
57.)
C'lutch
Sprfug
Pressure.
After
a considerable
mileage
it
may
be desirable
to
iacre€se
tbe
spring
pressurel
a little.
Firsl
drain
lbe
Pdmary
chain
oilbath
as
exDlain€d
oD
page
18
aDd
remove
tbe
outer
balf
of tte
oilbath
thus
exposiDg
tlle
clutch.
It
wil
be seetr that
the
clutch
Dlates
are compressed
togetber
by springs,
the
pressure
of which
is
coolrolled
by fte nu$
,
(Fig.
12)
aDd locktruls,4.
To
rncrease
-the
spring
pressurc,
release
thc locknuts
a!d.
tiShtcn
the nuts
B slightly.
It is important
that
each
ol
29
I
t.|
tl
|l
t1
fl
il
tl