[The Master Cylinder]

I use a needle adapter and just hold it in the hole on original fitting. https://www.amazon.com/gp/product/B0...GFA8STQHCP229D

But since I have changed out all fittings to modern zerk fittings. IMO they work much better with the 'check ball' to seal the end. Then i put a zerk fitting cap on the to keep them clean https://www.amazon.com/Bleeder-Greas...733747&sr=8-11