This should help out those of you who are about to replace your Blackbird's fork springs... or those who are simply replacing their nasty old fork fluid with fresh fork oil.

After you remove the fork off the bike, thoroughly clean that slider tube since you'll be pumping the fork quite a bit during this exercise, and you don't want any crusty bugs or other debris to dork up your fork seals as you work the forks:

CleanTube.jpg


Hopefully you remembered to loosen the 24mm top cap prior to removing the fork from the bike:

24mmTopNut.jpg

After the fork is removed and the 24mm top cap loosened, you can pull down the spacer tube to expose the 14mm locking nut . You (obviously) need to hold the top cap while you take a 14mm wrench to loosen the locking nut.:


14mmDamperNut.jpg



Now that the top cap is removed, you can remove the long spacer tube:


Spacer_Tube1.jpg


And pour out that nasty-ass old fork fluid (pour it in a measuring device if you *must* know the exact amount of fluid you removed):


DrainForkFluid.jpg


After the tube is close to being upside-down, get ready to catch the spacer ring and fork spring and they emerge from the slider tube. Pump the tube (and the damper rod) many, many times to try to get every last drop out that's going to come out. Some guys hang their forks upside down overnight (over a container, obviously) to get a thorough fork oil drain:


FinalDrain.jpg



As you can see, I only got about 15oz of fork oil out this fork:


FluidLevel.jpg

If you are installing new fork springs, remove the old springs at this time, and install your new ones.

Now it's time to put in fresh fork oil and set your air gap.

Whatever air gap measurement you elect to use, you take this measurement with the new fork springs NOT installed in the forks, and that the fork tube was supposed to be FULLY collapsed.

For instruction purposes, let's say you are after a 150mm air gap.

Basically, the procedure for obtaining the 150mm air gap height is to dump around ~375mm of fluid in the collapsed fork leg, reach in and pull the damper rod, and pump the damper rod up and down, *slowly*, a good 15-20 times so that the fluid is dispersed throughout the fork's inner workings. Now, again, with the fork springs NOT in the tube, and the fork leg *fully* collapsed, add suspension fluid until the level is exactly 150mm from the top edge of the fork leg (you can devise any measuring method you'd like.... some folks use a length of pipe cleaner, others simply use a ruler, etc .

Once you are happy with your air gap measurement, you reach in for the last time and pull out the damper rod to it's max extension, quickly slip the fork spring over it and "catch" the damper rod before it slowly settles back down into the tube (and you can no longer reach it since the springs are now in the way).

Now slip in the spring seat washer, and finally the long spacer tube. Thread on the top cap and lock it down with that 14mm lock nut seen above. Now just raise (extend) the slider tube up high enough so that you can thread that top cap down into the slider tube.

Torque down the top cap to spec, re-install the forks, and Go Ride!

THAT'S IT!!!!!
Thanks

nice workbook

Here's a tip for setting the air gap:

Measure the length you want it to be (the example says 150mm) and mark a piece of clear tubing at that length. Tape a piece of wire to the tube so it stays straight. Put the tubing down the pipe, and use a mity-vac to suck out the extra fluid.

Takes out the concern about whether you dumped in enough, or too much, and trying to get it exactly even.

Dale: Mostly out of curiosity, Why do you not remove the cartidge and let the oil drain out that way? This way you can clean the cartidge, too?

Do you rinse the interior with cheap oil before refilling, to flush it out ?

Question, how do you come up with the 150mm? Is there a formula, or rider size etc , that determines this messurment?

Lou

Originally Posted by lois

Question, how do you come up with the 150mm? Is there a formula, or rider size etc , that determines this messurment?

Lou

IIRC, that was the air gap recommended by Wilbers when we did the Group Buy in 2005.

The Service Manual calls for a 142mm air gap.

Thanks for posting this. How often do you change the fork oil on your bike?

Thanks Warchild.

Originally Posted by PJNXX

Thanks for posting this. How often do you change the fork oil on your bike?

At a minimum, every April.

This past year was a very heavy Endurance Riding year, so it got a second change in mid-July.

Every April? What does that equate to in mileage for you? On my last bike, a '96 VFR, I changed it at 20,000 miles when I also put in new fork springs. Do you change it every April because it gets dirty or breaks down like engine oil does?

No, it simply gets dirty when you ride approximately 35,000-40,000 miles a year... roughly split between the XX and the FJR.

Too, the mileage can add up fast when you don't own a cage....

Wow, yearly? Mine has gone almost 10 years with the original oil.... maybe it's time for a change!

Re, group suspension buy

I bought the new fork springs , replaced seals and dust boots etc. Instructions that came with the springs said to put the oil level @ 120mm which I did. The whole job from start to finish only took me about 3 hrs.

Going to try 7.5 weight Amsoil mix for my first go, if that doesn't work for me I'll go with a straight 10w next.


Either way, I won't know how the bike will handle with the new springs until I arrive in AZ this march....

Hi Dale,

Thanks for taking the time to explain this.

Due to financial reasons (my wife and kids are expensive) I was unable to join the group buy, but was able to finagle enough to buy new Race-Tech front springs.

I was talking to local dealer service tech (former racer) and he thought he could just drain the old fluid from a drain hole hidden/retracted in the front axle hole to drain the fluid, then remove mounting cap and put in new springs and 7.5weight oil. Now he was not looking at his shop manual, but he described the process a lot easier than this post.

What is your take on this? Are you just being a lot more thorough, or is this the only way to remove the oil and install new springs?

Thanks.

Dear Warchild
You know...I live in chile and here we are from de past century.
Friend I need your help

I'm changing the fork oil to my XX
I need to know grade and the amount of fluid

Thanks a lot