Maintenance
S.U.
Corburetter
If dirt or corrosion of the suction chamber, piston or piston rod
is
responsible then
the parts should be cleaned with a solvent such as petrol, thinners, degreasing fluid
or alcohol, but no abrasive material should be used. They should be re-assembled
dry and clean with OIL
ON
THE PISTON ROD ONLY. If, on the other hand,
there is metxllic contacr the high spot may be removed with a scraper PROVIDED
THAT
THE
GREATES?
CARE
is
TAKEN;
INDISCRIMINATE
SCRAPING
WILL
RENDER THE PARTS SCRAP.
Bent Needle
or
incorrectly centred Jet
A bent needle should be replaced as straightening is seldom satisfactory, and an
incorrectly centred jet should be re-centred according to the instructions given
below. In either case contact between these two parts
is
likely to have caused wear
and both may have to be replaced.
LUBRICATION
EVERY MONTH, or as frequently as may be found necessary, remove the plastic oil
cap from the top of the suction chamber and thoroughly oil the piston rod and guide
bush assembly with thin machine oil.
When the oil cap and joint washer have been replaced, ensure that the cap
is
FIRMLY
SCREWED DOWN. An
air
leak at this point would upset the automatic operation
of the piston in the suction chamber, causing a rich setting and loss of speed.
ECCENTRICITY
Re-centring of the jet
in
relation to the needle will be necessary should the jet have
become laterally displaced
in
service due to inadequate tightening of the locking
screw (IS), or any other cause. This operation will of course, also be necessary if
the let and
its
associated parts have been removed for any reascn. Before proceeding
as described in the next paragraph,
first
try turning the jet round
180°
as,
if,the jet
head has been connected
to
the mixture lever in a different place to that at which
it
was originally "centred" the action of the piston will be restricted.
The procedure for re-centring the jet
is
as
follows~-
The jet adjusting nut (18) should first be screwed upwards to
its
fullest extent,
THE JET HEAD THEN BEING RAISED
TO
CONTACT IT so that the jet assumes
its
highest possible position. The locking screw (15) should now be loosened sufficiently
to release the jet and the jet bush assembly (5), (13). (14),
etc
:and permit this to be
moved laterally.
A moderate side loading applied to the !ower protruding part octhe lower
jet
bush
(14). will indicate whether or not the assembly has been sufficiently freed. The
piston should now be raised and, maintaining the jet in
its
highest position, allowed
to drop. This will cause the needle to move the jet gradually but positively into
pzdtion, and thus bring about the required centralisation.
The locking screw should now be tightened and the jet returned to
its
former
position. Should any indication of contact between the needle and the jet persist,
which may sometimes occur due to further displacement of the assembly on finally
tightening the locking screw, this must again be slackened OH and the operation
repeated.
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