Karburator indstilling

N. 2 Dell'Orto Carburetors 'VHB 30 CD' (right) 'VHB 30 CS' (left).
Double controls:
  • throttle control grip, ('B' in fig. 1) right on the handlebar;
  • starter control lever for starting a cold engine, located on left cylinder head cover 'A': starting position, 'B': riding position.
Note:
When the starter lever is in riding position 'B' ensure that there is a clearance of about 3 mm. between starter control cable ends and adjuster screws on both carburettors.


Standard carburetor setting
Choke Ø mm 30
Throttle 40
Atomizer 265
Main jet 120
Idling jet 50
Starter jet 80
Needle V 9 (2nd notch)
Float 10 grams


Adjusting the carburation (fig. 1)

Adjusting by hand.
This adjustment is made as follows:
  1. Get the engine at its running temperature.
  2. Screw idling adjusting screws 'C' fully in; then screw them out by one turn and a half.
  3. By means of your hands feel if pressure at exhaust tubes is the same. In case of differences, act on screw 'C' of one carburettor until the pressure will be the same (idling speed will be kept at 900-1000 r.p.m. about; consequently it will be necessary to screw in the carburettor screw of the cylinder having a lower pressure or to screw out the carburettor screw of cylinder having a higher pressure).
  4. Get the best carburation for each cylinder by acting on screws 'C' (this will be at the point where the r.p.m. increase slightly) then get idling speed according to point 3.
  5. Disconnect one plug lead at a time and check that the engine stops after firing 5-6 strokes. If this does not occur, get it by proceeding as follows:
    - screw out screw 'C' of the cylinder causing the engine firing more than 5-6 strokes;
    - screw in screw 'C' of the cylinder causing the engine firing less than 5-6 strokes.
  6. Adjust idling speed to 900-1000 r.p.m. by screwing in or out in the same quantity screws 'C'.
  7. After closing the throttle control grip, check that there is a clearance of mm 1-1,5 between cable ends and adjuster screws 'E'.
  8. Check that both gas valves open at the same time by proceeding as follows:
    - Turn slowly the throttle control grip and check by means of your hands that the pressure at exhaust pipes increases simultaneously. In case such increase is not simultaneous, adjust the carburettor of the cylinder in question by screwing adjuster E in (after loosening its counternut) until the pressure is the same for both pipes.

Adjusting by means of a "Vacuum Meter"
To get a correct adjusting of carburation, it is advisable to apply to our dealers who can carry it out by means of a ”Vacuum Meter”.