AUC2107
Factory-Original SU piston spring.
This is the "Light Blue + Black" version with a load at length of 4.5 oz. @ 3.875 in.
It is recognizable by the paint on one of the ends (see photo but it is difficult to distinguish).

This particular spring is ONLY used on carburettors with a 2" throttle diameter:
These springs generate a resistance which balances the venturi size with the correct air flow and mixture.
Consequently, this spring is considered an important "tuning part" so choose yours wisely.
This product is priced, and sold, as a single unit.
Required quantity per carburetor: 1
This is an original SU part.
This is SU part number: AUC2107 / AUC 2107
* Made in the UK *