4) Diaphragm; 5) Jet Needle, Carburetor Piston - Rotax 914 F Maintenance Manual

13.1.2.4) Diaphragm

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See Pic. 63/64 and 65.
Unhook spring Q of choke from start lever W and chamber top E.
N NOTE:
1
For checking, remove the 2 countersunk screws T M5x12 and Allen screw
Y M5 along with nut and shim, remove the chamber top E and the spring
Pic. 64
8
U. Check tight fit of the cover I on chamber top.
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9
Remove plunger from the carburetor housing and remove 4 Allen screws }
M4x12.
Pic. 65
I ATTENTION: The position of the carburetor piston is controlled via the
Check diaphragm for cracks or brittleness, replace if necessary.

13.1.2.5) Jet needle, carburetor piston

See Pic. 63/66 and 67.
15
The jet needle e controls the fuel consumption at part load. It may be
1
regulated by choosing position of jet needle between 1 and 4.
2
3
Modifications are allowed only after consultation with the engine manufac-
4
turer.
N NOTE:
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Pic. 66
Remove fixation screw t and check jet nee-
dle e with circlip y for wear. Pay special
attention to the grooves and the taper of the
needle. At visible wear the jet needle must be
exchanged and refitted in the same position.
I ATTENTION: The jet needle fitted must
Visually check outside of plunger { and the
two inside compensation bores u.
Modification no.
- 0 -
The diaphragm R is linked to the plunger (carburetor
piston). Depending on the pressure prevailing, the plunger
is moved up or down.
Wash chamber top with cleaning agent and blow the inside
venting bore O with compressed air, then check visually. See Pic.
65.
N NOTE:
The diaphragm R is fixed by the retaining ring P to
the carburetor piston {.
diaphragm. On the diaphragm there are 2 positioning
noses. The nose q fits exactly in the recess in the plunger,
nose w must engage in the recess in the carburetor hous-
ing.
A higher position causes "deeper plunging" of the jet
needle into the needle jet r ™ smaller flow diameter ™
leaner mixture.
Lower position ™ richer mix-
ture.
move freely.
Reference
Pic. 67
19
Main Date
914 F 1997 02 01
00032
Page
127