Jet -DELLORTO (type: 6413)- 6mm (172)

The main jet is considerably involved in the mixture preparation of the carburetor.
If it is too small, the engine dies off under full load and/or runs so leanly that the piston and cylinder overheats and a cylinder damage would be the consequence.
If it is too large, the mixture becomes too greasy, the engine runs very unevenly and can only deliver a fraction of its possible power.
Here it is important to find the ideal compromise.

To determine the correct main jet, it is first of all chosen so large that the goal is an engine that stutters heavily under full load. Of course you need some experience, but a nozzle can be changed quickly. Once you have found such a nozzle, you mount a smaller one until the engine does not stutter under full load anymore.

secondary jet 4mm / 5mm

main jet 5mm / 6mm

jets.

The 6mm nozzles are exclusively used as main nozzle in the following carburettors:

PHBH, PHBL, PHBN, PHVA, VHSA, VHSB, VHSC, VHSH, VHST

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