Carburetor, fuel pump, throttle linkage,  M110

Cleaning carburetor



07.2—190 Cleaning carburetor


Identification: Information plate in national language on cross member in front of radiator or on cylinder head cover. Adjust engines according to data of respective exhaust gas information plate.


Testing and adjusting values


National version
Idle speed 1/min
Idle speed emission value % CO


up to 1976
max. 1.5




max. 1.0 without air injection






up to 1.5


1974 Federal


1974 California
6—8 without air injection


max. 1.0 without air injection


Vacuum governor1)


National version
Engine speed
Vacuum hose pulled off
Engine speed
Driving position engaged


TN choke
TN choke












M When all auxiliary units are engaged, the engine should still run smoothly.


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Float level


Float version
Float level1)


Flat roof float
-2 to 6 mm3)


Hip roof float and fuel return valve without fuel pressure regulation
0 mm2)


Hip roof float and fuel return valve with fuel pressure regulation
+ 2 mm2)


!) Measure from parting surface without gasket.
2)   In the event of starting or bypass faults, set 2 mm higher.
3)  Under parting surface.


Carburetor line-up


National version
s) 1976
<&«$> 1973
(usa) 1974 Federal
(usa) 1974 California


Carburetor designation
Solex two-stage downdraft carburetor 4 A 1


Carburetor stage
Stage I Stage 11
Stage I Stage II
Stage I Stage 11
Stage I Stage II
Stage I Stage 11


Main jet
X 105 –
X 105 –
X 100
X 112.5 –
X1052) –


Jet needle


Idle speed fuel jet
47.51) –


Idle speed air jet
102.51) –
102.51) –
102.51) –


M Combination jet
2)  Model year 1975, size 100
3)  Pressed-in, cannot be disassembled.


Special tools


Oil telethermometer
m110 - 0363-1.jpg
116 589 27 21 00


Digital tester
m110 - 0363-2.jpg
001 589 54 21 00


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Connecting cable 3 m long
m110 - 0364-1.jpg
000 589 04 90 00


Intermediate plug (adaptor)
m110 - 0364-2.jpg
000 589 72 63 00


m110 - 0364-3.jpg
000 589 71 63 00


Conventional tools


Revolution counter and CO measuring instrument


Self-made tool


refer to Fig. item 9


m110 - 0364-4.jpg
1    Remove air filter.
2   Thoroughly clean outside of carburetor.
3   Loosen all fastening nuts and screws on carburetor cover. Pull off lock (43) and disconnect choke rod. Unscrew air filter fastening screw.


Press off carburetor cover only at pressing-off point.
m110 - 0364-5.jpg


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4 Clean filter strainer with compressed air.
m110 - 0365-1.jpg


5 Unscrew idle speed jets or combination jet (238). Blow out jet and duct with compressed air.
m110 - 0365-2.jpg
78 Idle speed air jet


Combination jet
238    Idle speed and idle speed fuel jet
239    O-ring
m110 - 0365-3.jpg


6 Remove main jets (79). Blow out all ducts, bores, riser pipes and jets with compressed air.
Do not clean jets with metallic items (e.g. wire, drill).
m110 - 0365-4.jpg
79 Main jets stages I 149 Jet needles stage II 158 Riser pipes bypass system stage 11 193 Riser pipes starting mixture enrichment 224 Riser pipe TN choke (thermostatically controlled bypass choke)


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7 Blow out injection bores (arrows) of accelerating pump with compressed air and check for unobstructed passage (clean injection bores with a 0.5 mm drill, if required).
Check jet line-up. Install all parts.
m110 - 0366-1.jpg


8 Remove holddown (34), float (32) with float needle valve.
m110 - 0366-2.jpg


9 Pull out closing plug for intake port (suction duct) of accelerating pump with self-made puller. Lift valve ball out of duct (e.g. welding wire with grease).
m110 - 0366-3.jpg


10 Clean float chamber and ducts (200, 203, 204, 187) with compressed air.
m110 - 0366-4.jpg
187   Vent bore
200   Intake port
203    Idle speed mixture ducts
204   Vacuum bore for controlling enrichment


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11 Clean feed bores (165) and reserve chambers (164) with compressed air.
m110 - 0367-1.jpg
164 Reserve chamber for bypass system stage II 165″ Feed bore for reserve chamber stage II


12 Check suction valve for leaks. For this purpose, install valve ball (5 mm steel ball). Fill float chamber with fuel. Slip suitable hose over suction duct (intake port), keep both delivery valves (arrow) closed, on carburetors with vent bore (187) also keep these bores closed and blow into hose. No or only indivi­dual air bubbles should come out of intake bore and enter float chamber.
m110 - 0367-2.jpg


In the event of leaks, knock lightly against suction valve seat with steel ball (5 mm dia.). Insert new steel ball and check once again for leaks. Then close intake port (suction duct).
m110 - 0367-3.jpg
187 Vent bore
Arrow = delivery valve


13 Check delivery valves for leaks. For this purpose, slip suitable hose over a delivery valve, keep other delivery valve closed, on carburetors with vent bore (187) keep this bore also closed and blow into hose. No or only individual air bubbles should come out of suction bore (200) and enter float chamber. Then check opposite delivery valve.
In the event of leaks, knock balls of delivery valves “lightly” against their seat.
m110 - 0367-4.jpg


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14 Check float level and adjust, if required. For this purpose, push connecting web (arrow) up to noticeable stop in downward direction and check float level with­out gasket.
To avoid measuring faults, make sure that the float shaft rests on base of housing during test.
m110 - 0368-1.jpg
Measuring float level with flat roof float


Measuring float level with hip roof float
m110 - 0368-2.jpg


Correct float level, if required, by rebending at speci­fied bending point (arrow).
m110 - 0368-3.jpg


15   Attach float needle with wire clip on float arm in such a manner that the open side of clip points in driving direction.
16    Install float (32), making sure that the float shaft rests on base of recesses. Insert holddown (34). Holddown should project slightly over parting surface. Rebend, if required.
17    Mount carburetor cover with new gasket.
18   Mount air filter.
19   Adjust idle speed (07.2-100).
m110 - 0368-4.jpg


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