Fork Oil Change

[Zero Knievel]

In the last 3 month I tried different fork oil viscosities.

[snip]

Agreed. I thought it was interesting how the different weights of oil for different weight riders worked out...and it makes some sense. If you're a light person, you'd probably find the stock suspension too stiff. If you're "husky" you might be happy with stock or need stiffer, and wear would be more noticeable because of your weight.

I'm doing the forks and putting in stronger springs because there is too much dive in the front end now, and that was the likely sign that the fork job was overdue...I don't remember it diving so harshly when I first got the bike.

[BASTOK]

The only thing I know I that my next bike would or MUST have front suspension settings. A bike like the XX, considering for what she was built and the performance she can show must have something to set the suspension, and not having to take out the hole front to try.

Byeeee

[Zero Knievel]

Here is Hobicus' instructions in PDF (subject to revision).

*EDIT* PDF updated

FORK_JOB_INST_1.1.pdf

[BASTOK]

.................................On instruction #18, when you get to the steps for suctioning out excess fluid, step #3 reads "with the tube all the way DOWN...." I need to know if that means the fork tube fully compressed or fully released/uncompressed. I should change the wording to be less confusing.

It reffers to the Main tube of the fork, the one that is chromed. It has to be fully compressed, the same as the damping rod, fully compressed.

Remember you have to do that WITHOUT the springs, spacers, etc etc.

Hope this helps

[Zero Knievel]

Two questions. Got the forks taken apart, cleaned and reassembled w/o fluid.

1. I cleaned the cartridges by spraying them down with brake cleaner and wiping them down. I pumped them until nothing more came out, but I didn't think to submerge them in kerosene and pump them. Should I do that before I finish the job or did I get them clean enough? At this stage it would not be a major inconvenience since parts are just snugged down and not torqued.

2. I thought last time I did an oil change on forks (Kawasaki) I had to pump the forks after the job was done. I'm thinking about air pockets in the forks from filling with fluid. Either I missed it in the directions or it's not needed, but would it be wise to lock and open fork into a vise, fill with some fork oil and manually pump the cartridge (no resistance) to "burp" out all the air before putting it completely together?

[Redbird]

1) Good enough, I wouldn't bother dismantling them again.

2) Yes, you have to cycle the damper rod a few times to evacuate any air. Do this with the fork open and before you set oil height.

[tomek]

If you are positively,absolutely sure there is no old oil left you can go by the amount specified in service manual ( 483 +/- 2.5 ccm) and scape setting oil level .

Auto body shop supply stores sell disposable paint mixing cups ( 20-50 cents each) that are perfect for this.

[cecome]

1) Put the bike on the center stand

2) Remove the front fender

3) Remove the handle bars/clip ons. Loosen the allen, wiggle them up and loose. Make a note of what lines run where, you will be thankfull when you're re-assembling everything.

3) Loosen (break free only!)the bolts on:

The front wheel (4 12 mm bolts, 1 22 mm big bolt.

Both brake calipers, including the ones for the LBS and the lines.

Using a 24 MM socket, loosen the fork caps.

4) (if you have a front end stand, that goes inside the steering stem, you can skip this step)

Put a block of wood on your jack, and roll the jack under the oil pan and jack up the front end until the front wheel is off the ground. The bike should be pretty stable. if it wobbles on the wood, re-position it and try again.

5) Remove the brake caliper bolts on the right side of the bike, and work the caliper loose.

6) remove the 22 mm nut holding the axel in place, and pull the axel out. Make a note of where the spacers in the wheel are, you will thank me later.

7) Remove the rest of the caliper bolts from the fork, loosen the 10 mm bolts where ever the brake lines mount to the fork tubes.

8) Once you have all the brake lines free, there's a 14 mm and an allen holding each fork tube in place. Loosend the fork tube, and it will drop right out.

9) Before you do ANYTHING ELSE, spray the fork tube down with Honda Polish (or equivalent) and clean up any bugs/dirt/etc that might be on the tube. This will help keep your seals from leaking.

10) I remove the allen bolt from the bottom of the tube when I do mine. I just makes emptying them so much easier, and certainly more thorough. I usually need to take the fork, and putting the base in my vise, I can usually just break it loose. I do each side. IF it will spin but not come free, I take it out of the vice and with it upside down (note, I have not removed the end caps yet!) I push down on it, and turn the allen. That usually works. As long as the end of the allen isn't boogered up, you can also try using a longer Allen with an impact wrench, and spin it out.

IF the end is boogered up, I just remove the fork top, since getting it out is going to be a giant pain.

11) With the allen out, when you turn the fork over, oil will start to leak, so put the end in a bucket ,and remove the top fork cap (you loosened it before you dropped them, but you may still need to put a wrench on it to get it to come free. Once you get the cap loose, the oil will flow pretty quick. Find the brass washer behind the allen bolt, sometimes it gets stuck up inside.

12) To pull the cartidge out, you will need a 14 mm wrench to loosen the nut under the fork cap. Loosen the nut, and the cap will come all the way off. You can then pull out the spacer and spring. Make a note of the order and orientation of the spring, so you can put it back together the same way. (as I remember, it's narrow end down)

13) Pull the cartidge out, and pump it a BUNCH of times. You will find that it takes quite a bit to get the oil out of it. I have been known to spray it down with brake cleaner to clean it up, too.

14) I usually clean up the spring and spacer as best as I can, using a shop towel and occasionally using some brake cleaner. In the end, you want to make sure everything's as clean as possible.

15) When cleaning inside the fork tube, it's usually a good idea to rinse it out a bit with oil too. You also want to clean the underside, where the allen bolt will seat with the brass washer. It's a good idea to plan on replacing the brass crush washer. I've reused them on a regular basis without incident, but I did have one incident where it leaked. As it turned out, I had not cleaned the underside well enough (Where the brass washer seats, and it left enough dirt on there that it leaked.

16) To re-assemble, first put the cartridge inside the fork tube. I usually put the spring and the spacer/washers in as well, without oil, and put the fork cap in place, too. Then I start the allen which holds the cartidge in (see above about the brass crush washer and getting the dirt out of there!) until it's tight. Pushing down on the fork tube, compressing the internal spring, is usually good enough to get it to snug down nice and tight. Your shop manual will have a torque spec, but it's been my experience that it's usually worth taking down to the vice and making sure it gets nice and tight.

Note: some people like to put permatex on the bolt for extra leak protection. Like I said, if you get the surfaces nice and clean, you should be OK, but it's your call.

17) Once the cartridge is back in, you take the fork cap off, and remove the spacer and spring, too.

There's 2 schools of thought as to how to fill the tubes with oil:

1) Measure with a graduated cylinder.

2) Over fill and use a Mity Vac to extract any extra.

Because the only way to know if you got it full is to measure how much oil's in there, I use the 'Over fill and Extract" method, as taught to me by Redbird. I don't remember the stock height (230 MM comes to mind, but I will check my manual when I get home and update the post. EDIT 142 MM, not 230!) But basically here's the process:

Fill the fork tube most of the way up with oil. Pump the inside cartridge up and down about 20 times. After the first few times, you'll find that it gets much tougher to move, as it's filling up with oil. Try to work it the full length of travel. After you're sure you got all the air bubbles out, you're done.

Tape a piece of wire with the tube on your Mity Vac (to keep the tube straight). Measure from the bottom of the tube up to the height you want it to be (so.. 142 mm, or 14.2 cm) and mark the tube. A smart guy bends the wire so it can hook on to the tube, but make the mark as accurate as possible.

Holding the fork upright, without the spring or spacer in there, with the tube all the way DOWN, (having a helper here makes it much easier) put the Mity Vac tube inside the fork tube down to your mark. Now suck out any extra fluid, holding the tube at the mark the whole way. When you start sucking air, you've got it to the proper level.

[uPDATE 4/23/2008: According to my service manual, for 99-03 XX's, that number is 142 MM, or 5.6 IN, not 230 as previously posted]

After that, it's pretty straight forward:

18) Put spring, washer and spacer in fork. Tip: Pull up on the inside cartridge first.

19) Attach cap to the cartridge top. Spin down to the to pof the 14 mm nut. note that the goal here is to get them even. so make sure the nut is at the same level (and tight!) on both sides.

20) Push the cap into the tube, and tighten. This can be somewhat tricky, and a helper is usually good here if you need someone to hold things. If you dont' get it super tight, that's fine, just get it snug.

21) Put the fork tube back in the bike. Raise it up until it's 1.5 inches (I will dig up my manual, as listed above, but that's what I remember) fromn the bottom of the fork cap to the top of the triple tree. Tighen down up at the top tree first (because it's easy to get to) but don't forget to tighten the 14 mm bolt on the lower tree, too.

When fishing up the forks through the trees, pay special attention to the position of the wires and brake/clutch lines, they should be where they were when you pulled the fork out.

22 ) Once the forks are back in the trees tighten down the caps one more time, now that you can torque them properly.

23) Replace Handlebars - Do not pump brake handle, though!!!

24) I usually take this time to spray the brake calipers with cleaner and push the buttons/pads back inside the caliper. Makes assembly easier, and you'll be amazed at how good your brakes feel for a while

25) Install brake line bolts in the forks, and put the front wheel on (check direction of spin) Snug the front axel bolt, but not the 4 pinch bolts.

26) Lower the bike off the jack. Torque the front wheel bolt.

27) Install the brake calipers. Note that while a properly torqued bolt shouldn't fall out, I would recommend using at a minimum blue loctite on the caliper bolts. I HAVE had them fall out.

28) Pump up the brakes. Make sure they are nice and working.

29) Using the brakes, bounce the bike on the new forks.

30) Tighten the pinch bolts on the fork tubes. (Yea, I know, it's silly, but that's how the manual says to do it)

31) Replace the fender.

As with any major change to the bike, before you go balls to the wall, take it easy for a bit on your first trial ride.

How long do you think it would take someone who has never made the attempt before? I plan on working with rideonXX and letting them hang overnight but maybe not pulling the carts themselves...also thought about throwing some cleaner in the night before the forks are pulled...any thoughts?

[BearXX]

1) Put the bike on the center stand

2) Remove the front fender

3) Remove the handle bars/clip ons. Loosen the allen, wiggle them up and loose. Make a note of what lines run where, you will be thankfull when you're re-assembling everything.

3) Loosen (break free only!)the bolts on:

The front wheel (4 12 mm bolts, 1 22 mm big bolt.

Both brake calipers, including the ones for the LBS and the lines.

Using a 24 MM socket, loosen the fork caps.

4) (if you have a front end stand, that goes inside the steering stem, you can skip this step)

Put a block of wood on your jack, and roll the jack under the oil pan and jack up the front end until the front wheel is off the ground. The bike should be pretty stable. if it wobbles on the wood, re-position it and try again.

5) Remove the brake caliper bolts on the right side of the bike, and work the caliper loose.

6) remove the 22 mm nut holding the axel in place, and pull the axel out. Make a note of where the spacers in the wheel are, you will thank me later.

7) Remove the rest of the caliper bolts from the fork, loosen the 10 mm bolts where ever the brake lines mount to the fork tubes.

8) Once you have all the brake lines free, there's a 14 mm and an allen holding each fork tube in place. Loosend the fork tube, and it will drop right out.

9) Before you do ANYTHING ELSE, spray the fork tube down with Honda Polish (or equivalent) and clean up any bugs/dirt/etc that might be on the tube. This will help keep your seals from leaking.

10) I remove the allen bolt from the bottom of the tube when I do mine. I just makes emptying them so much easier, and certainly more thorough. I usually need to take the fork, and putting the base in my vise, I can usually just break it loose. I do each side. IF it will spin but not come free, I take it out of the vice and with it upside down (note, I have not removed the end caps yet!) I push down on it, and turn the allen. That usually works. As long as the end of the allen isn't boogered up, you can also try using a longer Allen with an impact wrench, and spin it out.

IF the end is boogered up, I just remove the fork top, since getting it out is going to be a giant pain.

11) With the allen out, when you turn the fork over, oil will start to leak, so put the end in a bucket ,and remove the top fork cap (you loosened it before you dropped them, but you may still need to put a wrench on it to get it to come free. Once you get the cap loose, the oil will flow pretty quick. Find the brass washer behind the allen bolt, sometimes it gets stuck up inside.

12) To pull the cartidge out, you will need a 14 mm wrench to loosen the nut under the fork cap. Loosen the nut, and the cap will come all the way off. You can then pull out the spacer and spring. Make a note of the order and orientation of the spring, so you can put it back together the same way. (as I remember, it's narrow end down)

13) Pull the cartidge out, and pump it a BUNCH of times. You will find that it takes quite a bit to get the oil out of it. I have been known to spray it down with brake cleaner to clean it up, too.

14) I usually clean up the spring and spacer as best as I can, using a shop towel and occasionally using some brake cleaner. In the end, you want to make sure everything's as clean as possible.

15) When cleaning inside the fork tube, it's usually a good idea to rinse it out a bit with oil too. You also want to clean the underside, where the allen bolt will seat with the brass washer. It's a good idea to plan on replacing the brass crush washer. I've reused them on a regular basis without incident, but I did have one incident where it leaked. As it turned out, I had not cleaned the underside well enough (Where the brass washer seats, and it left enough dirt on there that it leaked.

16) To re-assemble, first put the cartridge inside the fork tube. I usually put the spring and the spacer/washers in as well, without oil, and put the fork cap in place, too. Then I start the allen which holds the cartidge in (see above about the brass crush washer and getting the dirt out of there!) until it's tight. Pushing down on the fork tube, compressing the internal spring, is usually good enough to get it to snug down nice and tight. Your shop manual will have a torque spec, but it's been my experience that it's usually worth taking down to the vice and making sure it gets nice and tight.

Note: some people like to put permatex on the bolt for extra leak protection. Like I said, if you get the surfaces nice and clean, you should be OK, but it's your call.

17) Once the cartridge is back in, you take the fork cap off, and remove the spacer and spring, too.

There's 2 schools of thought as to how to fill the tubes with oil:

1) Measure with a graduated cylinder.

2) Over fill and use a Mity Vac to extract any extra.

Because the only way to know if you got it full is to measure how much oil's in there, I use the 'Over fill and Extract" method, as taught to me by Redbird. I don't remember the stock height (230 MM comes to mind, but I will check my manual when I get home and update the post. EDIT 142 MM, not 230!) But basically here's the process:

Fill the fork tube most of the way up with oil. Pump the inside cartridge up and down about 20 times. After the first few times, you'll find that it gets much tougher to move, as it's filling up with oil. Try to work it the full length of travel. After you're sure you got all the air bubbles out, you're done.

Tape a piece of wire with the tube on your Mity Vac (to keep the tube straight). Measure from the bottom of the tube up to the height you want it to be (so.. 142 mm, or 14.2 cm) and mark the tube. A smart guy bends the wire so it can hook on to the tube, but make the mark as accurate as possible.

Holding the fork upright, without the spring or spacer in there, with the tube all the way DOWN, (having a helper here makes it much easier) put the Mity Vac tube inside the fork tube down to your mark. Now suck out any extra fluid, holding the tube at the mark the whole way. When you start sucking air, you've got it to the proper level.

[uPDATE 4/23/2008: According to my service manual, for 99-03 XX's, that number is 142 MM, or 5.6 IN, not 230 as previously posted]

After that, it's pretty straight forward:

18) Put spring, washer and spacer in fork. Tip: Pull up on the inside cartridge first.

19) Attach cap to the cartridge top. Spin down to the to pof the 14 mm nut. note that the goal here is to get them even. so make sure the nut is at the same level (and tight!) on both sides.

20) Push the cap into the tube, and tighten. This can be somewhat tricky, and a helper is usually good here if you need someone to hold things. If you dont' get it super tight, that's fine, just get it snug.

21) Put the fork tube back in the bike. Raise it up until it's 1.5 inches (I will dig up my manual, as listed above, but that's what I remember) fromn the bottom of the fork cap to the top of the triple tree. Tighen down up at the top tree first (because it's easy to get to) but don't forget to tighten the 14 mm bolt on the lower tree, too.

When fishing up the forks through the trees, pay special attention to the position of the wires and brake/clutch lines, they should be where they were when you pulled the fork out.

22 ) Once the forks are back in the trees tighten down the caps one more time, now that you can torque them properly.

23) Replace Handlebars - Do not pump brake handle, though!!!

24) I usually take this time to spray the brake calipers with cleaner and push the buttons/pads back inside the caliper. Makes assembly easier, and you'll be amazed at how good your brakes feel for a while

25) Install brake line bolts in the forks, and put the front wheel on (check direction of spin) Snug the front axel bolt, but not the 4 pinch bolts.

26) Lower the bike off the jack. Torque the front wheel bolt.

27) Install the brake calipers. Note that while a properly torqued bolt shouldn't fall out, I would recommend using at a minimum blue loctite on the caliper bolts. I HAVE had them fall out.

28) Pump up the brakes. Make sure they are nice and working.

29) Using the brakes, bounce the bike on the new forks.

30) Tighten the pinch bolts on the fork tubes. (Yea, I know, it's silly, but that's how the manual says to do it)

31) Replace the fender.

As with any major change to the bike, before you go balls to the wall, take it easy for a bit on your first trial ride.

How long do you think it would take someone who has never made the attempt before? I plan on working with rideonXX and letting them hang overnight but maybe not pulling the carts themselves...also thought about throwing some cleaner in the night before the forks are pulled...any thoughts?

I did it first time last year.

Took them of and removed the cap, spring, spacer and shim.

Emptied in a bucket and pumped the rod several times.

Let them hang upside down over night. Then filled up

and sucked out the excess. I let the screw in the bottom be.

Couldn't be easier.

The oil wasn't black and greasy and still looked new.

So I didn't bother using cleaner.

[RXX]

This is a good place for me to start!

[SwampNut]

I used this guide, maybe not word for word but to help me smoothly move through a spring change and new oil on the current XX.  Can confirm, it helped a lot.

 

Also, love the HyperPro progressive springs.  I used their oil also.

 

https://epmperformance.com/products/hyperpro-fork-spring-kit-honda-cbr-1100-xx-blackbird-sp-ho11-ssa001

 

 

[tomek]

 Well, front fork is progressive as is even with straight rate springs because on the top of well, springs, air gap between the oil and top of the fork is being compressed as fork dives. 

 So, if you want to make fork feel more progressive/reduce dive increase fork oil levet vs. OEM spec by 5-10 mm and see of you like the change. Or less progressive decrease level. Ohlins has that cute graph showing effective fork rate change vs. fork oil level in their front fork race kits.

 

 Throwing progressive spring on suspension that already is progressive by design is mildly retarded IMHO. So, if you wanna less dive under braking increase oil level as described above, if that does not work for you get stiffer straight rate springs. 

 

 Maxima 5W race fork fluid (blue bottle) works well with stock OEM valving on XX.

Edited October 6 by tomek

[RXX]

25 minutes ago, SwampNut said:

I used this guide, maybe not word for word but to help me smoothly move through a spring change and new oil on the current XX.  Can confirm, it helped a lot.

 

Also, love the HyperPro progressive springs.  I used their oil also.

 

https://epmperformance.com/products/hyperpro-fork-spring-kit-honda-cbr-1100-xx-blackbird-sp-ho11-ssa001

 

 

 

What do you think about/how hard would it be to make a forum specifically for Blackbird related repairs? 

The OCD in me envisions a filing cabinet marked "Blackbird" with folders like "electrical" with subfolders for wiring harness, stator, battery, etc.

I would find that pretty useful.

[tomek]

[SwampNut]

It's easy, but also, even easier and probably cleaner to use the tags feature.  Both the posters and any mods can add tags.  Your opinion?

 

Pros for tags:  Multiple tags possible for a thread like this that cross over many fixes.

 

Cons:  ?

 

 

 

 

[fizzy]

4 hours ago, tomek said:

 Well, front fork is progressive as is even with straight rate springs because on the top of well, springs, air gap between the oil and top of the fork is being compressed as fork dives. 

 So, if you want to make fork feel more progressive/reduce dive increase fork oil levet vs. OEM spec by 5-10 mm and see of you like the change. Or less progressive decrease level. Ohlins has that cute graph showing effective fork rate change vs. fork oil level in their front fork race kits.

 

 Throwing progressive spring on suspension that already is progressive by design is mildly retarded IMHO. So, if you wanna less dive under braking increase oil level as described above, if that does not work for you get stiffer straight rate springs. 

 

 Maxima 5W race fork fluid (blue bottle) works well with stock OEM valving on XX.

I am going to change fork oil this winter.  Standard valves, straight would springs, you say use 5W instead of OEM spec 10W? 

Been using this brand engine oil in bike(s) for years, no issues. 

High Performance 5W 5wt Motorcycle Fork Oil Suspension Fluid 1 Litre 1L | eBay UK

[SwampNut]

I found that I'd get excessive dive and bottoming for my riding usage and style, which would be worse with lighter oil.  180 pounds and I generally ride tight to the tank with some handlebar pressure.  Configured as HyperPro suggested as far as oil weight and level, all that is gone.  You can of course keep raising the oil level to do some amount of compensation, but of course, this has some side effects and air can behave strangely.

[tomek]

 Viscosity effects high speed dumping the most. High speed indicates here how fast fork is sliding. So, in practical term how it works when hitting bumps like cracks on the surface of the roadway. Fork dive under braking is not high speed. lt is considered low speed and is not effected much by oil viscosity. Spring fork rate, valving and oil level are at play here. You don't deal with fork dive by changing oil viscosity because it has not much effect on it. So, going with 5W will remove some harshness from the front fork without having much effect on anything else, and you can bump the oil level s little bit as well to reduce the dive.

 

 Also, really, when changing the rate of the spring at one end of the bike the other side has to be somehow compensated as well. Otherwise, when leaned over and suspension being loaded by centrifugal force, how the bike feels and acts will change because one end will seat lower or higher. That changes chassis geometry.

 

 

 

 

[tomek]

On 10/6/2026 at 5:32 PM, SwampNut said:

 You can of course keep raising the oil level to do some amount of compensation, but of course, this has some side effects and air can behave strangely.

What would be the air strange behavior? And side effect that is not already there?

 Air is mix of couple glasses and, maybe, but not in Arizona, H20 vapor. Totally predictable behavior.