I asked this a while ago because I bought the screaming eagle heavy weight fork oil but could not figure out how to drain the old oil out. Just got my issue of American Cycle Mag and they have an article for a lowered fork kit for their Street Bob. The drain plug runs at the bottom of both fork legs, in-line with the fork tubes. There is a hole at the bottom of the fork leg bottom side that does not split so you can access the drain plug.
Will do and report back.

 

lets see pics of this discovery......

 

I was told the screw on the bottom of the fork secured an internal part - the damper or whatever - dont have a schematic or parts breakout

So i just did as all suggested and poured the oil out of the top, I posted a step by step in an article few days ago - it was easy as cake

 

DON'T UNSCREW THAT SCREW!

 

That is not a drain plug or screw. That is the allen bolt which secures the seat pipe to the lower slider. It may be very difficult to loosen, but even more difficult to tighten. There is a good chance there is not enough tension on the seat pipe to hold it so the seat pipe bolt can be properly tighten and torqued. If such is the case, you will find yourself disassembling the tubes and sliders.

Do it right. Reomove the tubes from the trees, turn them over, and drain them.

 

according to the parts manual it is a screw

screw (right hand) part # 4042

when i removed mine i used a breaker bar, screwed right off

 

indeed, that is NOT a drain plug...that holds the dampener in place......HOWEVER, if you unscrew it just a bit, you will lose fluid......just don't unscrew it all the way....use it to "bleed" the fluid out....that's what i would do

 

So what is the problem with unscrewing it all the way? I did just that when I had to fix a leak on the right fork leg.

 

Keep an eye out for a pre 06 dyna and you will see a little phillips screwon the trailing side of the lower fork. That screw is a drain screw to drain out fork oil. To the best of my knowledge the newer bikes have to remove the forks to drain them.

 

You have to take the front tire/axle off to get to the seat pipe screws so why not loosen the four pinch bolts and take the tubes out and open fork caps to drain the right way. Will take way less time and you got to take the caps off anyway to refill with oil. Guess I don't see the point of loosening the seat pipe screws if you don't have to I took mine apart to do lowering springs and chrome sliders it was a bitch to get them tight enough to not leak when done. Do yourself a favor drain from the top it will take less time and give you less headache.