Main Jets for SI Carburettors from SIP PERFORMANCE by KOSO for precise tuning in the mid and upper speed range.

The Main Jet sits in the SI Carburettor in the Nozzle Fitting below the Mixer Tube and Main Air Correction Jet. It is responsible for providing an appropriate amount of fuel for premixing. With every tuning measure, no matter how small, the Main Jets must be adjusted or enlarged, as they mainly affect the mid and upper rev range. Their effect is very closely related to the other parts of the middle SI Nozzle Fitting. For a comprehensive tuning, all components involved must therefore be adjusted accordingly.

Recently, DELL'ORTO has been increasingly unable to supply important nozzle sizes over longer periods of time. Imprecise replica nozzles from the existing aftermarket are not an alternative for us. That is why we now have our own SIP-marked jets produced by KOSO.

While DELL'ORTO jets can vary by +/- 0.05 mm within a size, the maximum deviation for SIP jets is +/- 0.005 mm. Anyone who has ever tuned a Carburettor and could not rely on the embossed sizes knows what we are talking about. For example, where it says 105, it must be 105. Otherwise you will quickly lose interest in tuning.

The size of the jets increases in steps of one, two and three. The jets get progressively fatter. Simply add the corresponding size to item no. 4026. The jets from size 142 are also produced under the SIP PERFORMANCE logo, as DELL'ORTO can only supply jets up to 140. The SI 105-128 and 130-140 Jetting Kits contain 5 and 10 jets respectively and are an ideal basic program for every tuner.

Conclusion: Best quality, very precise, perfect price-performance ratio and finally available again on a regular basis.