A) Carburettors without mixture bypass system
Before synchronizing carburettors, make sure that valve clearance,
dwell angle and ignition timing are set corectly.
Engine must be at normal operating temperature.
Remove entire air cleaner housing.
Disconnect rod from rear carburetor.
Connect air cleaner simulator 13 00 000.
Instructions for use are given on the next page.

Carefully screw in both mixture adjustment screws until tight,
then unscrew them by approx. 1½ ÷ 2 turns.
Unscrew stay bolt only when synchronizing carburetors by means of the
Motor-Meter.

Start engine.
At 900 rev/min, synchronize throttle butterfly position of the two
carburetors by turning the idling speed adjustment screws.
a) Using Motor-Meter: in both carburetors, the pistons in the riser
pipes must be at the same leight.
b) Using synchronizer made by the Korinth company, Steinheim/Main,
West Germany:
indicator reading must be the same on both scales.
c) Using United synchronizer made by the Schubert company,
Ingolstadt, West Germany (see photo):
indicator must point to 0 (zero).
Set eingine speed to maximum idle speed by turning both mixture
adjustment screws.
Correct engine idling speed to 900 rev/min.
Repeat this procedure as often as necessary until engine idles
at 900 rev/min. Engine idling speed must always be adjusted
finally by means of the mixture adjustment screw.

Adjust length of linkgage rod so that engine speed is not changed
when rod is connected.
Install the complete air cleaner housing.
Note: When the air cleaner housing is installed, the engine
speed will drop by approx. 100 rev/min.
Increase engine speed again to max. idle speed by turning
mixture adjustment screw.

B) Carburetors with mixture bypass system
Before work starts, the engine must be at normal operating
temperature (oil temperature at least 60° C (140° F).
Remove the screw plugs from the exhaust manifolds and insert
test probes 7062.
Connect the exhaust emissions tester.

Take off the air cleaner 13 71 000.
The drop in engine speed which accurs when the cleaner is removed
can be compensated for by attaching special tool 13 0 000 to the rocker cover
Connect the secondary breather.
Warning: If special tool 13 0 000 is not available, the idle
speed will drop by about 100 rev/min when the air cleaner is
installed again.
Disconnect rod (2).



13 71 000

Connect the synchronizer¹.
a) With the two additional mixture regulating screw (3) and (4),
adjust idle speed at the two carburetors alternately until a value of
900 ÷ 1000 rev/min is obtained.
Synchronization is correct when the tester points to zero (0).
b) Adjust CO content of the exhaust at each carburetor idle mixture
regulating screw until a value of 2.0 ± 0.5% CO is obtained.
c) If stage b) causes the idle speed to change, repeat stages a) and b)
until idle speed returns to 900 ÷ 1000 rev/min and the CO content of
the exhaust does not exceed 2.0 ± 0.5%.

Adjust length of connecting rod (2) with the knurled nut
until the engine idle speed remains the same when the rod is
reconnected.

Caution! The carburettor´s air flow rate is set by the manufacturer.
Resetting stop screws (7) is not permitted.
The following adjustment may only be carried out in an emergency case -
for exmaple when the throttle valve sticks or the specified idle speed is
not reached.
Detach connecting rod (2).
Tighten both auxiliary mixture control screws (3 and 4) until tight.
Remove plastic caps and synchronize the engine speed to 700 rpm with
the stop screws (7) and at the same time adjust the CO level per carburettor
to 3% with the idle mixture control screws (5 and 6).
Lock the stop screws (7) with plastic caps.
Synchronize the engine idle speed to 900 to 1000 rpm and the CO level
to 2 ± 0.5% with the auxiiary mixture control screws (3 and 4) and the idle
mixture control screws (5 and 6).

If difficult to synchronize:
Check pressure rod setting A = 40 mm (1.575").
Synchronize carburettor - see 13 00 004.


13 00 004