1. trondd

    trondd Loyal Comrade

    How does one go about tuning the Trabi carb? I've got a 28HB-2 and the only adjustments are idle mixture and idle speed.

    I don't quite get the interaction between the mixture adjustment and the throttle speed adjustment. The idle "mixture" adjustment seem to be more about how much of the mixture and not the richness of the mixture, as that's accomplished by the size of the idle air jet and idle fuel jet as far as I can tell.

    So what do I adjust the mixture for? Highest RPM sounds silly if it's just opening up the tap. The manual states it's tuned from factory for lowest CO but I can't measure that. On a "modern" carb you can tune for highest vacuum but the Trabi has no vacuum ports.

    Do you just set it to 2 turns out then tweak the rpm with the idle speed screw and just get on with it?
  2. A Spooky Ghost

    A Spooky Ghost Loyal Comrade

    The mixture screw is for the low speed circuit. In other words- the fuel air ratio, at idle. When it is working right, the idle will smooth out, or get worse depending on the way you turn it. A good way to do this is to :

    Warm the car up, make certain the choke is all the way off. Then set the idle speed a little bit higher than normal. Now play with that mixture screw until it sounds the smoothest/ and has the highest idle. There is a bit of a delay, after you turn the screw. It is not a instant change.

    Lastly turn the idle screw down to your liking.

    Tada you did it!

    While you are there, put your hand over the opening of the carb- it should instantly die(remove carb elbow first). If you removed the metal carb elbow, and it then runs while your hand is over it- " You have a leak somewhere!". Case halves, cylinders, carb base, and or crank seals :eek:.... Just sayin.
    Last edited: May 1, 2019
    RogerDerSchrauber likes this.

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