Below is a basic explanation of the different parts of a Dellorto PHBG carburetor, the carburetor in the example picture is a 17.5-millimetre Dellorto PHBG replica.
- Choke: in this case it is a manual choke. A cable-operated choke is also available for the PHBG carburettors. Then the choke can be operated with the help of a cable on the steering wheel, for example.
- Manifold connection: In this case, it is a slide-in model, meaning that the carburettor slides over the manifold. There are also slide-in models of the PHBG carburettor available, meaning that the carburettor is attached to the manifold by means of a rubber.
- Float chamber: it fills with petrol, this is also where the nozzles that supply the moped with petrol are located. Later we will go into more detail about the function of these different nozzles.
- Fuel hose connection: This is where the petrol hose is attached directly.
- Idle screw: With this screw you adjust the idle speed. If the screw is turned further in, the moped gets more petrol and more air. If the screw is turned further out, the rpm drops.
- Air screw: The air screw can be used to control the air supply very precisely.
Below is a picture of the contents of the float chamber. We elaborate on the function of the various parts
- Float: The float floats on the petrol and cuts off the petrol supply at the right time. The petrol supply should be shut off when the float is horizontal.
- Float pin: The pin is attached to the float. When the float goes up, the pin pushes the supply of petrol closed. Attached to the float pin is a small rubber cap that fits exactly into a seat through which the petrol runs.
- Main nozzle: The main nozzle supplies petrol to the moped. The main nozzle is mounted in the nozzle tube. In the nozzle tube, the throttle needle moves up and down when accelerating. The more gas is given, the further up the throttle needle goes. So that determines how much petrol and through the main nozzle and nozzle tube goes into the manifold.
- Main idle nozzle: However, this non nozzle is not replaceable because there are simply no alternatives for it.
- Idle nozzle: The idle nozzle controls the supply of fuel at low rpm. This nozzle often has a small size, this is because the supply at low revs only needs to be minimal.
Original and replica Dellorto PHBG carburetors
We have original and replica PHBG style carburetors. There are several differences between the replica and the original version:
- The original carburetors often have 2 extra connections on both sides. These are 2 connections pointing straight down. These are overflow connections, on which a hose can be slid. If there is unexpectedly too much petrol in the carburettor, it can drain from here.
- The text indication on an original carburetor is different from a replica version. With an replica carburetor only the size of the carburetor is indicated. Original carburettors are printed with the original PHBG logo, also the loose parts are often printed with an INC code. This is a code for original Dellorto parts.
- The overall finish of an original Dellorto is naturally a bit nicer than with an replica Dellorto carburetor.
- When replacing parts from an original carburetor, it is wise to check whether there are codes or dimensions on the old parts. If so, the parts to be replaced should match the new ones.