RM CARBURETORS

Solex and Mikuni PHH Sidedraught Specialists

Updated 15/01/2022

If you have problems please ask. If you have tips or jetting please advise and I can add info to this page.

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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 from the information contained in the Mikuni PHH Carburetor Service Manual and Toyota's service manuals that cover Solexes used in 2T-G and 18R-G powered models.

Here are pictures which identify the location 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 central balance arrangement found on 2T-Gs and 18R-Gs will come shortly.

There will be another couple of pages linked off this page with more tips and advice shortly as I re-learn how to add and edit the links.

Mikuni Jetting Table

When Mikuni sold the PHH40 and 44mm as a performance option they provided an initial jetting specification 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 own jetting 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

Jet Block 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

Typical Toyota 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

32

Inner Venturi

10.5-14

10.5-14

Throttle Plate

#165

#165

Jet Block Assembly

5.8 - (6x2.5 & 4x1.5)

5.8 - (6x2.5 & 4x1.5)

Bleed Pipe

T

M

Fuel Needle & seat

1.5

1.5

Pump Jet

45/40

35

Idle Mixture/Pilot Screw

1.0 turns

1.0 turns

Tuning Tips Page 2

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Updated 15/01/2022