If the slide is opened a little, a negative pressure occurs which means the petrol is sucked upwards through the calibrator. While the mixer tube and needle determine the quantity of petrol, the throttle slide controls the amount of air which is added. The cylindrical throttle slides of the DELL'ORTO PHB series are fitted with different sized cutaways. The bigger this cutaway is the more air is added to the petrol. The mix that then results is correspondingly leaner than that on the throttle slides with a small cutaway. We stock DELL’ORTO throttle slides for the PHBL carburetor from 30-60 as well as the slides for the PHBH carburetors from 30-70.

Conclusion: Together with the mixer tube and needle, necessary under all circumstances for optimum tuning in the partial load range.