Carburettor adjustment for BMW R75 H-P
Hommes
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You
have to synchronize the engine to make it run smoothly. An absolute requirement
for this is a mechanically perfect condition of the carburettor and the correct
equipment of carburettor jets. The following items
have to be controlled:
-
Clearance
of the carburettor slide in the
housing 0.02-0.06 mm
-
Float
and carburettor piston needle undamaged
-
All
jet ports clean and in the right size
-
Original
equipment of jets
-
No
damage on housing
-
The
surface where you put the screws has to be absolutely flat
Today it is nearly impossible to get well overhauled
Graetzin carburettors. Nowadays you can get carburettors from new production.
Visually they look just like the original, but you have to change the
carburettor jets and adjustments..
Spare parts for BMW R75 Hans-Peter Hommes Kamphausen 170 D-41363 Jüchen Germany Fax +49 21 66 606670
e-mail
hphommes@wehrmachtsgespann.de
The
basic adjustment of the idling speed ( Do not let the engine run )
- Turn the screws of the accelerator cables completely
into the carburettor cover
- Turn the air regulation screw as far as it will go
and then 1.5 turns back again
-Turn out the carburettor slide adjustment screws until the slides are completely
closed, turn the screw back in again until they touch the carburettor slide and now further turn
- Start the engine and let it warm up.
- Remove the spark plug connector and turn the air
screw as long as the working cylinder is
true
running and has reached its highest
speed
- Repeat the adjustment with the other cylinder
- Put back the spark plug connector
- The synchronisation
of both carburettors is done with the carburettor slide adjustment slide screw.
By turning it in or out both carburettors will become homogeneous and the idle
speed is achieved. To do this you need a lot of feeling and good hearing.
-Adjust the clearance of the accelerator cables with
the tuning screws at the carburettor covers to 0.5 mm
- Accelerate briefly, the engine
should not splutter and swallow
If the exhaust
smoke is soot-black the mixture is too rich: Turn the air regulation screw out.
If the engine splutters or
swallows the mixture is
probably not rich enough.
You
can remedy the matter by turning the air regulation screw further in and you put
the piston needle higher.
If
you have taken the above action and you have still not achieved a perfect idling
speed then you have to control the adjustment of the engine (clearance of valves,
valve timing, ignition).
This translation is out of the book
Wehrmachtsgespanne gestern und heute
von H-P Hommes ã 1997