Bent Needle Or Incorrectly Centred Jet; Eccentricity - Triumph SPEED TWIN 1945 Workshop Instruction Manual

Maintenance S. U . Corburetter
If d i r t o r corrosion of t h e suction chamber, piston o r piston r o d
is
responsible then
t h e parts should be cleaned w i t h a solvent such as petrol, thinners, degreasing fluid
o r alcohol, b u t n o abrasive material should be used. They should be re-assembled
d r y and clean w i t h O I L ON T H E PISTON R O D ONLY.
If, o n the other hand,
there is metxllic contacr t h e high spot may be removed w i t h a scraper PROVIDED
THAT THE GREATES? CARE
is
TAKEN; INDISCRIMINATE SCRAPING WILL
RENDER T H E PARTS SCRAP.
B e n t N e e d l e o r i n c o r r e c t l y c e n t r e d J e t
A bent needle should be replaced as straightening is seldom satisfactory, and an
incorrectly centred jet should be re-centred according t o the instructions given
below. In either case contact between these t w o parts i s likely t o have caused wear
and b o t h may have t o be replaced.
L U B R I C A T I O N
EVERY M O N T H , o r as frequently as may be found necessary, remove the plastic o i l
cap from the t o p o f t h e suction chamber and thoroughly o i l the piston rod and guide
bush assembly w i t h thin machine oil.
W h e n the o i l cap and joint washer have been replaced, ensure that the cap i s FIRMLY
SCREWED D O W N . A n
a i r
leak at this point would upset the automatic operation
of the piston i n t h e suction chamber, causing a rich setting and loss of speed.
E C C E N T R I C I T Y
Re-centring of t h e jet
in
relation t o the needle w i l l be necessary should the jet have
become laterally displaced
in
service due t o inadequate tightening of the locking
screw (IS), o r any other cause. This operation w i l l of course, also be necessary if
t h e l e t and
i t s
associated parts have been removed for any reascn. Before proceeding
as described i n the next paragraph,
f i r s t
t r y turning the jet round 180°
as,
if,the jet
head has been connected
to
t h e mixture lever i n a different place t o that at which
it
was originally "centred" t h e action of the piston w i l l be restricted.
The procedure f o r re-centring the jet
is as
follows~-
The jet adjusting n u t (18) should first be screwed upwards t o
i t s
fullest extent,
THE JET HEAD T H E N BEING RAISED TO C O N T A C T I T so that the jet assumes
i t s
highest possible position. The locking screw (15) should now be loosened sufficiently
t o release the jet and t h e jet bush assembly (5), (13). (14),
e t c
:and permit this t o be
moved laterally.
A moderate side loading applied t o the !ower protruding part octhe lower
jet
bush
(14). w i l l indicate whether o r n o t the assembly has been sufficiently freed. The
piston should now be raised and, maintaining the jet i n
i t s
highest position, allowed
t o drop. This w i l l cause the needle t o move the jet gradually but positively i n t o
pzdtion, and thus bring about the required centralisation.
The locking screw should n o w be tightened and the jet returned t o i t s former
position. Should any indication of contact between the needle and the jet persist,
which may sometimes occur due t o further displacement of t h e assembly on finally
tightening the locking screw, this must again be slackened OH and the operation
repeated.