This might sound like a stupid question but, when adjusting pilot screws to 2.25 turns out, is this 2 x 360 degree turns of a screwdriver & one 45 degree turn or just two turns ( 2 x 180 degrees plus a bit)?

Ah the lovely pilot screw question.

1 turn is 360 degrees.

So two turns is 720 degrees.

2 1/4 is 810 degrees.

It helps to put a felt tip mark on your screwdriver handle, turn it till the mark is back to the original position and thats 1 complete turn (360 degrees) :-)