I am right now in a project to change out the forks on my '03 UC to get rid of the cartridge on the left side, and end up with the '06 and above configuration. So the procedure that 89Stroker descibes above is the one for my bike after the change. This is already the procedure for my little bike ('91 Dyna). I would add the step of stroking the forks a few times once the oil stops flowing out of the drain holes.
Additionally, I would measure the amount of oil out of each side, and put that amount back in if you know that the levels were right and even to start with. The only way to know that is to have followed a procedure to measure the air gap above the oil and to have set it per the HD spec, or as adjusted to suit. What I did to determine that for my new forks is the following:
- With the forks off the bike, drain the oil out by removing the spring keeper nut, removing the spring and invert the fork into a container
- Pump the tube a few times to get the rest out
- Turn the fork upright and put anything back that came out except for the spring
- Remove the drain plug and drain out all that will come out
- Pump the tube a few times to get the rest out and replace the drain plug
- Collapse the tube as far as possible
- Measure the tube
- Extend the tube as far as possible
- Measure the tube
- Calculate the difference and write that down (mine was 3.500")
- Measure the spring keeper nut from the shoulder to the top and write that down (mine was 1.125")
- Collapse the tube all the way
- Add the recommended amount of shock oil (mine was 350ml)
- Remove the excess oil to establish the specified air gap (mine was 4.88" or 4 7/8")
- Insert the spring in the tube (dense end down)
- Measure the air gap with the spring in and tube all the way down and write that down (mine was 2.125")
- Add up the figures you wrote down - this is now the air gap that you will want with the fork fully assembled (mine was 6.750")
- Assemble the fork and check the air gap
- Mount based on Factory Service Manual procedure
TQ