How do you set the mixture on a SU carb?

With the engine running at working temperature, hook your finger under the pin and raise the piston about 1/32in. (1 mm). If, while the piston is raised, the engine speed increases briefly then returns to normal, the mixture is correct. If it rises and stays high, the mixture is too rich.

How do you tune a single SU carb?

HS Type Carburetter: Tuning Single Carbs (b) Turn the jet adjusting nut/screw (2) down/clockwise, to enrich or up/anti-clockwise to weaken, until the fastest speed is indicated; turn the nut/screw up/anti-clockwise until the engine speed just commences to fall.

How do I know what model SU carb I have?

Carburetter Identification

1. The specification number which appears on a metal tag attached to the carburetter by one of the float chamber or suction chamber screws.
2. The position in relation to the driver.
3. By the interconnection between the throttle and the starting enrichment system on the carburetter.

What does SU carb stand for?

Skinners Union
George Skinner together with brothers John and Carl formed the S.U. Carburetter Company in 1910, setting up business in a small workshop in London. The initials S.U. stand for Skinners Union.

How do you measure SU carb size?

The size is measured at the throttle/engine side.

Do SU carbs have accelerator pumps?

Since it relies on restricting air flow in order to produce enrichment during acceleration, the throttle response lacks punch. By contrast, the fixed choke design adds extra fuel under these conditions using its accelerator pump.

Are SU carbs any good?

The SU is a good carburetor, fairly inexpensive, easy to tune unless they are warped, and easy to modify except for metering needles. I do not know the current supply of off-the-shelf metering needles. It used to be limited; and when we were still working on SU’s, we made most of our own.

Which is the correct type of SU carburettor?

SU Booklets – AUC9939A (AKD7902): Type HIF carburettor tuning & servicing SU Booklets – AUC9939A (AKD7902): Type HIF carburettor tuning & servicing V8 Register 21.12.06 Copyright of SU Carburettors is acknowledged 2 SU Booklets – AUC9939A (AKD7902): Type HIF carburettor tuning & servicing

What’s the best way to tune a SU HS4 carburetor?

The Uni-Syn is much easier to use, and can result in better balance. Alternatly adjust the idle screw on each carb, attempt to set the idle as low as possible (~800-1000 RPM). Adjust until the airflow is *close* to the same at each carb. The engine may now be running rough, just keep the idle speed high enough to keep running.

How to tune single carbs multi-SU carburetters?

(c) Tuning Single Carbs item 5 shows the correct type of exhaust smoke. (a) Tighten the clamp bolt of the throttle spindle interconnections and set the link pin lever with the pin resting against the edge of the pick-up lever hole (see inset). This provides the correct delay in opening the front carburetter throttle disc.

Which is the best manual for carburetor tuning?

Mikuni HSR 42-8 42-19 45-2 45-3 45-4 Carburetor Evo & Twin Cam Instruction Manual HERE Pekar K-68 Carburetor Adjustment Guide Service Manual Dnepr & Ural Motorcycles HERE