Technical Information Sheet for the Restoration of the BMW R75 and Zündapp KS 750.
Monthly available on our website.
H - P Hommes
© 2011 h-p hommes
Carburettor Solex - Idle
Many KS 750 drivers have the problem not to be able to
adjust the carburettor so that it brings a low idle.
Either the engine is running too fast or it stops.
If the jet assembly is correct, the problem is often due to the lack of the rubber seal around the idle jet or an incorrect throttle flap.
The Solex carburetors that were used for cars have a different throttle flap, which does not permit the regulation of the KS-engine to a low revolution speed.
It only helps to replace this throttle flap valve against a KS-throttle flap.
Our order no. 1027-1
The idle air screw is not responding.
The idle air screw to adjust the mixture does not change the revolution speed.
With this screw the necessary amount of air is supplied to the petrol that is coming via the idle jet while the throttle flap is closed.
Set the motor at idle to the lowest possible revolution speed.
Now out of the basic position (1.5 turns turned out), the optimal setting is determined.
Screw and unscrew the idle air screw slowly.
When the engine begins to run smoothly, the setting is correct.
Next screw is - fettigeres mixture
Next unscrew results - lean mixture
If you screw it any further the mixture is too rich
If you unscrew it any further the mixture is too lean
Should an adjustment be possible because the engine fails to respond, then the following causes could be responsible.
- Wrong throttle flap
- Too much play in the throttle flap shaft axles (false air)
- Missing seal around idle jet
- Incorrect or worn jet assembly
New nozzle set with oversize axle
New jet assembly with oversize
Our order no. 1027
The axle hole in the carburettor can only be reamed with a very special reamer.
Trying to enlarge one hole after the other usually has the effect that the axle has too much play again.
In our workshop we can completely restore your
H-P Hommes Ersatzteil-Dienst
Ersatzteile + Instandsetzungen
repairing + restoring
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