Raket 95 Owner's Manual - page 23
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Raket 95 Manual - English
23
drops of fuel down onto the needle valve
and pump up the pressure on your pump.
At approx. 1.0 kp/cm2 the inlet valve
should open and after that it should re-
lease air through it down to a pressure of
approx. 0.5 kp/cm2. Now the valve should
be totally sealed! If this test does not
appear to have worked properly then the
question is, what should we do next? The
most common problem is probably that
the valve is not sealed, and in that case
one must search for dirt or pores or else
change the needle valve. PLEASE NOTE!
Leaking gaskets on the pump side will ex-
hibit the same symptoms. If the opening
or sealing pressure is not correct then you
will have to change the spring and lever
until it does appear to be correct.
OK – now the valve is correctly adjusted.
What other faults could exist? The master
diaphragm – maybe?! It is most likely so
that far too many master diaphragms are
changed for no good reason. There are
strong forces at work on the diaphragm.
One should really be able to feel that it
has become stiff before it is definitely time
to change it. Check the gasket (that is
lying closest to the carburettor casing on
this side of the carburettor).
Assuming that you have cleaned the car-
burettor properly and that the High Speed
and Low Speed screws are not damaged,
then there is really not too much more
that can be wrong.
The only thing that remains now is to
check if the engine is difficult to start and
if it refuses to react when the setting of
the L-needle is changed. In that case
there could be dirt under the expansion
cap that is located beneath the master
diaphragm. The fuel from the Low Speed
needle passes through a small chamber
on its way out to the venturi and on very
rare occasions this chamber can become
clogged. In such a case one should bore
a 2 mm hole in the middle of the cap (nr
20) and then pry it away using a sharp
object that one can stick into the hole.
Thereafter you should carefully check
all of the channels running to and from
the chamber and seal those with a new
expansion cap that you must carefully
put in place using a mandrel 8 mm. Now
there should not be any more faults with
your carburettor.
Normally these diaphragm carburettors
are extremely reliable. They are devel-
oped for use with chainsaws and snow-
mobiles. On very rare occasions one may
come across a carburettor that does not
provide satisfactory performance. In that
case you should borrow an identical one
if possible. If you notice a large difference
in the performance of the carburettor you
have borrowed compared with your own
then you should change your carburettor.
It is more or less a practical impossibility
to alter the fuel channels in a carburettor
on one’s own.
4. Starter equipment
On engines that are equipped with a
manual coil starter (or Magnapull starter),
the coil or the return spring may need to
be changed. The basic rule regarding an
eventual change is that the return spring
may never be drawn to such an extent
that it causes a stoppage for the coil when
it is fully drawn. A small amount of “give”
should always exist in the spring when the
coil is fully drawn.