The regulator valve is suppose to keep the oil pressure from getting to high. ¹⁾
See more on the Oil Pressure Regulator in the Evo section of the Sportsterpedia.

The oil pressure relief valve is factory set to open between 30-35 psi.
The stock spring can get weak and open too soon which will dump oil into the cam chest prematurely instead of where it is needed. ²⁾
And your low oil pressure light will never go off.
You can replace the stock plunger spring with a 5/8“x2” spring of heavier gauge from your local hardware store.
This will render the plunger inoperable as there will now be too much oil pressure needed to overcome the increased spring pressure.

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