Replacing the Blackbird's Fork Springs

Warchild

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:




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



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.:






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





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):





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:






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




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!

__________________
- Warchild
http://www.superblackbird.com/

redxxrdr

THAT'S IT!!!!!
Thanks

Aiki

nice workbook

Hobicus

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 ?

__________________
-- Rich

I love my country but fear my government

lois

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

Lou

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SORRY HONDA....I COULDN'T WAIT ANY MORE.

Warchild

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.

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- Warchild
http://www.superblackbird.com/

PJNXX

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

__________________
-Paul

SSUXX

Thanks Warchild.

Warchild

At a minimum, every April.

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

__________________
- Warchild
http://www.superblackbird.com/

PJNXX

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?

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-Paul

Warchild

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....

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http://www.superblackbird.com/

Jette

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

lois

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....

__________________
SORRY HONDA....I COULDN'T WAIT ANY MORE.

Venus97

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.

Baupres

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

Warchild

Hello Baupres -

You can't go wrong with using the HondaPro SS-8 fork fluid that is standard from the factory. If I recall, SS-8 is actually 10wt fork fluid (someone correct me if I am wrong)

That having been said, many experience Blackbird owners (who have not modified their forks) use a somewhat thinner oil that the factory, because sadly enough, the forks are significantly overdamped (as well as undersprung) from the factory. A thinner oil with pass through the various orifices at a faster rate, which helps reduced the effect of an overdamped fork.

I personally use Silkolene 5wt Synthetic fork fluid. But again, most fork fluids on the market are pretty damn good, so you should worry more about obtaining the proper viscosity.

Regarding the amount of fluid.... the Blackbird Service Manual states the forks take 483 cc's of fluid. However, this is for completely empty, "dry" forks. It is far more important to set the air gap properly. If you're staying with stock fork internals, then stay with the air gap Honda recommends, which is 142 mm. Just follow the above instructions for setting the air gap, and you'll be fine.

__________________
- Warchild
http://www.superblackbird.com/

jjmcjames

Thanks Dale...just a heads up-when I changed mine I was going with the Hyper Pro springs and oil. The original oil was so dirty I did not see the small spacers-when I drained the oil they fell into the container. After finishing the job and disposing of the old oil I found them-had to take both of them back apart to install the spacers-easy to miss.

Baupres

thanks a lot ..... now to do this

dunedain

You're likely gonna need bushings if you've waited that long. I'm an every other year guy on oil but I split my riding between MX, Enduro, Sport Touring, Track, Supermoto....... so my maint schedule is at critical mass.

If I was in Dale's place I'd go yearly too.

Dale, Excellent write up as normal!

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fifer1967

Hi there,

I have read in alot of magazines about cartidge inserts that make your stock front suspension fully adjustable....!!!!!!

Any one ever done one of these kits? they come complete and even come with oil....and set up info.

The kits are usually advertise in tuning mags etc

Cheers

Warchild

You are referring to the Traxxion AK-20 Cartridge Kits. I installed them in the spring of 2006.

They are exquisite. Although brutally expensive.

We did a kick-ass Group Buy on them last year, and they were still horribly expensive.

And worth every penny. See: CBR1100XX - Traxxion Group Buy

__________________
- Warchild
http://www.superblackbird.com/

fifer1967

Hi there,

Did you do the rear shock option as well....

Do you know if a cheaper option like heaver oil and progressive springs is worth while?

Cheers

Warchild

Oh, I replaced the shock looooong ago, well before this AK-20 kit.

It is apparent to most assertive XX owners that Honda shipped the Blackbird quite undersprung and over-damped as it comes from the factory.

So replacement springs, yes, definitely. The stock XX is significantly undersprung, so new Eibach or Ohlins fork springs, at a spring rate appropriate for your weight/riding style, is definitely indicated.

However, you want to AVOID using heavier oil on the stock fork setup, as the forks are already overdamped from the factory (i.e.: suspension fluid can't move through the orifices/shim stack fast enough as it is). Putting heavier oil in their just makes it that much slower. Your ride will be harsh and you might even experience chatter in some situations.

So UNLESS you are going the whole route with new fork internals, etc, stay with the stock viscosity. Or, more ideally, go with something a little thinner yet. I use the 7.5wt Silkolene myself, and after I replaced my springs (the first time, before the AK-20 conversion), I even went down to 5wt.

__________________
- Warchild
http://www.superblackbird.com/