Throttle Slide SIP for tuning SI carburettors. For Vespa Engines in which the middle and lower part-load range is to be specifically greased.

The Throttle Slide limits the air flow to the Engine. Its degree of opening is determined by turning the Throttle Grip. The wider it is open, the more air can flow. Some Throttle Slides have air pockets on the top and cut-outs, so-called cutaways, on the bottom. These add additional air to the fuel mixture, thereby reducing its volume. Sliders with a flat underside do not add any additional air and are therefore ideal for compensating for a middle section that is too lean.

Throttle Slides with two additional air pockets are fitted to the SI carburettors currently supplied in order to comply with the required exhaust values of the new PX. However, these lean down the mixture so much that tuned Engines can experience anything from part-load ringing to piston sticking. The solution to the problem: simply replace the installed Throttle Slide with a richer Throttle Slide without air pockets. The SIP Throttle Slides are now also available in versions 4.1 (cut-outs 50% of the original size, therefore slightly fatter in the middle/lower range) and 4.2 (without cut-outs, therefore significantly fatter in the middle/lower range).

Conclusion: Throttle Slides are often overlooked in carburetor tuning and are the icing on the cake in SI tuning.