Solex mikuni 4040

Tuning Tips
This is a page I intend to fill up with some basic maintenance, common problems and tips to help sort out the tuning of Solex/Mikuni sidedraughts.  These are in addition to and come fromthe information contained in the Mikuni PHH Carburetor Service Manual andToyota's service manuals that cover Solexes used in 2T-G and 18R-G powered models.
Here are pictures which identify thelocation of most of the parts used for and during  tuning, shown on an S5 type.  These parts and relative locations can be related back to all the other Solex/Mikuni types. A picture of a typical centralbalance arrangement found on 2T-Gs and 18R-Gs will come shortly.
                

Mikuni Jetting Table
When Mikuni sold the PHH40 and 44mm as a performance option they provided an initial jettingspecification with each carburetor.  This is a good place to start when applying the Solex and Mikuni to performance or competition use.  Toyota and other manufacturers using the Solex had their ownjetting tables which changed constantly, as required through the evolution of the motors using them.
From Mikuni's manual:
Description | Size for PHH40 | Size for PHH44 |
Main Jet | 140 | 150 |Main Air Jet | 180 | 200 |
Pilot Jet | 57.5 | 57.5 |
Pilot Air Jet (fixed) | 140 | 120 |
Outer Venturi | 32 | 34 |
Inner Venturi | 12-16 | 10.5-14 |
Throttle Plate | #165 | #175 |
JetBlock Assembly | 5.8 - (6x2.5 & 4x1.5) | OA |
Bleed Pipe | T |   |
Fuel Needle & seat | 1.5 | 1.8 |
Pump Jet | 40 | 40 |
Idle Mixture/Pilot Screw | 1.0 turns | 1-1/8 turns |
TypicalToyota Jetting
There are now so many jetting sets out there that this can only be typical examples.  Please, if possible refer to the Service manuals.
Description | Solex S5 40mm typically on 2T-Gs |Solex Type T  typically on18R-Gs |
Main Jet | 125/135 | 135/140 |
Main Air Jet | 150/180 | 200/140 |
Pilot Jet | 55/57.5 | 63.8 |
Pilot Air Jet (fixed) | 80 | 120 |
Outer Venturi | 28/32 |...