Here are the tools you need the top is the valve tool (if you don't have one get a long 3/8" course thread bolt like the one in the middle) and a 5/32"  allen wrench 

1st the bolt take the barrel off the gun and make sure the hammer is all the way forward 

Then sick your allen wrench down into the bolt 

Here we see the bolt screw all the way open turn the screw counterclockwise closes off the hole 

hole is half closed

all the way closes

As you turn the screw you will feel a click this comes from the notches in the screw and a small ball bearing under the back o-ring as you turn the screw the ball bearing gets pushed up as it comes out of the notch (seen here) and will go back down when it goes back in this is when you will feel the click

To get at the valve adjustment take the bolt , hammer and spring out of the gun 

****Note make sure the gun has no air in it at all at this piont******

now look in side you will see a  dot  on the valve ( as you can see here the valve is at the 6 o- clock position 

****Note make sure the gun has no air in it at all at this piont******

Here you can see witch hole size goes with what clock position the bigger the hole the higher the velocity  

****Note make sure the gun has no air in it at all at this piont******

screw you valve tool into the valve clockwise

****Note make sure the gun has no air in it at all at this piont******

****Note make sure the gun has no air in it at all at this piont******