I have bought new pins and grommets for my clutch and brake I have fitted them OK but can't get the grommet to stay in the little recess it pulls back towards the lever when I let go any tips or advice to get this grommet to stay where it is ment to

Make sure it's clean, and rotate the grommet a few times so it gets seated properly.

OK will give it a clean and try spinning it is it right to just push the pin through the grommet and then put the spring on the other side

The master cylinders on the Beta are Grimeca, so if you got pins and rubbers meant for another make of master cylinder, the rubbers may have a different diameter and not locate in the undercut.

Also some of the pins are 2mm longer and cause problems trying to adjust the clutch or brake as you can't screw them out far enough.

The advert I bought from says what I bought was for ajp and grimeca master cylinders so I thought must be OK maybe not will compare with old ones tonight

The pins are both the same length 22mm

Diesel   With all else being equal, the reason they are popping out is due to  a vacuum being created by the movement of the pin through the rubber boots.

 

Put plenty of Armor All on the rubber boots and be patient they will loosen up.