The needle/float carburettor is particularly sensitive to different modifications and, given the many adjustment possibilities, preparation and competence in the choice of calibration is a rquirement. So, basically the first thing you need to do when buying a second-hand bowl/needle carburetor is to check that all the elements it is composed of are in line with a standard calibration table. In fact, there are standard setups communicated directly by manufacturers that allow you to have a good starting point for calibrating it properly. Precisely these “factory settings” offer a sort of lifeline when you buy a used product: this is the starting point, the certainty of having reliable settings, and then you can proceed with the fine tuning. This is why the carburetor must be dismantled and all the removable elements (which can be changed/replaced) need to be checked, including: the pulverizer, the conical needle, the max float valve needle, the off-idle float valve needle, the emulsifier of the off-idle circuit, the float. and the fuel inlet valve. After checking the components inside the used carburetor, it is advisable to always replace the petrol inlet housing and the fuel inlet needle. In fact, these two components ensure fuel sealing and its constant level inside the tank, fundamental conditions for correct and safe operation of the carburetor.
The versatility of the VHSH 30 means the carburetor can be used for different engines. Precisely for this reason - and because of the number of possible adjustments - it could be the case that your VHSH 30 carburettor, after having been returned to the factory standard calibration, does not have the correct setting for the engine it is combined with. In fact, engine manufacturers buy standard carburetors with standard setups from DELLORTO, but before selling them in combination with their engines, they adjust them according to the strong points and performance of the engines. This is why it is always good to ask the engine manufacturer whether the standard calibrations are suitable. If in doubt, or if you cannot find this information, for the first use we recommend adopting a careful approach with a richer mixture, increasing the max float valve needle and the off-idle float valve needle and raising the conical needle by a notch, compared to the indications of the standard settings, thereby avoiding seizure problems.
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