The main air correction jet on the SI carburettor is located above in the jet block above the main jet and calibrator. It determines the premix ratio of the petrol and the air and enriches the petrol in the jet block with oxygen. It primarily effects the lower and middle rev range, meaning in the area of the 1/4 to 3/4 of the opened throttle slide. If the cubic capacity is enlarged the main air correction jet should also be adjusted. In most cases it also needs to be enlarged. The DELL'ORTO main air correction jets are available for the SI D/H/E and the SI G carburettor. As they increase in number (this indicates the size of the air hole), the main air correction jets get increasingly leaner.
Conclusion: A must for perfect carburettor tuning in the lower to middling rev range.
SIP-TIP: Experiment with the mixter tube and different main jets as well.
SIP community user 'hofmeisterud' on part no 58270000: "Superb quality!"
CAUTION: Please take notice that we use DELLORTO jets exclusively. It doesn't make sense to save a few cents and use copy-cat jets. Those who've tuned carburetors and found the actual jet size does not correspond to the number engraved on the side, know what we're talking about. If 105 is on it, then there'd better be 105 in it! Anything else is a cheap trick.