HOW TO: Change your fork seals

(Note: These intructions were developed while working on a 1981 XJ650H and should be adequate for all 650 models up to 1983. Other models will very in design.)

You noticed it sometime back, but ignored it hoping it would go away. But, it hasn't. In your embarrassment, you quickly wipe off your fork tubes when meeting friends for fear that they might say something. Worse yet, it's gotten so bad that your front brake pads have become contaminated with fork oil and you've got oil spatters all over the front of your riding pants.

Well, my friends, it's time to do something about it. Today, we're going to tear into those troublesome forks and replace those pesky seals. And then you can ride in confidence knowing that you've got a clean looking machine.

Today we'll be working on my trusty steed:



I ride an '81 XJ650H Maxim.

...and here's the problem:



Before we get started, let's quickly review all the parts to a front shock:



(Click this image for a larger version.)

As I step through the directions, I'll refer back to this image by placing in brackets each part's corresponding number. For example, if I say to remove the cap bolt, I'll follow it with [15] so that you can look at this picture for clarification.

Here are the steps...
1. Place the bike on a level surface and on its center stand.
2. Using a jack, raise and support the bike so the front tire is off the ground.

Note: you will want to make sure the bike doesn't rock back and forth on the center stand with the front wheel off the ground.

3. Remove the front axle cotter pin and discard. Loosen and remove the axle nut and washer.



4. Slide out the axle, tapping gently with a hammer if necessary.
5. Remove the speedometer gear and remove the tire.
6. Remove the bolts holding the front fender and the brake caliper(s). See arrows for locations.



Moving to the top end of the forks, we'll next need to remove the handlebar to gain access to the cap bolts[15], circlips[17], etc. Note: if you have a fairing, you may need to remove it to complete the following steps. Also, on some models, removal of the handlebar isn't required as it doesn't cover the end of the fork tubes. If this is your case, skip to Step 9. Another option is to break the shocks down after removing them from the bike. If you choose this option, skip to Step 13. You may need to refer to Steps 9, 10, 11, and 12 for information on removing the fork springs[11].

7. Remove the plastic center cover and the handlebar clamp bolt dust covers. Loosen and remove the handlebar clamp bolts and clamps.



8. Remove and set aside the handlebar.



9. Remove the fork caps[16] covering the cap bolts[15] and circlips[17].



Note: On some models, the cap bolts[15] will have an air valve for filling the shocks with air. If you have this style, you will want to let the air out by depressing the valve before removing the cap bolt[15].

10. Using a clamp, compress the fork spring[11] by pushing down on the cap bolt[15]. This will allow you to pry out the circlip[17].



11. Remove the cap bolt[15]. Replace the o-ring[12] if it has become damaged. Remove any rust that may be present on the cap bolt[15].



12. Slide out and set aside the fork spring[11].
13. Remove the drain plug[18]. Drain the fork oil into a suitable container. Raise and lower the shock several times to remove any remaining oil. Replace drain plug[18] when finished.



14. Next, we'll need to loosen, but not remove the upper and lower shock pinch bolts.





15. Using a wedge or large-bladed screwdriver, pry apart the lower pinch clamp to allow the shock to slide down and out.



16. Insert your cylinder holding tool (or something similar) into the fork tube. This tool can be purchased from chacal or one can be built from scratch using a spark plug socket turned upside-down.



17. Flip the assembly over and remove the cylinder securing bolt[20] from the bottom of the fork assembly.



Here you can see the three separate parts of the shock assembly:



18. Remove and discard the old dust seal[6], oil seal clip[4], and oil seal[5], being careful not to damage the outer fork tube[2] in the process.

Here are the new parts we'll be installing:


(Thanks, Len!)

19. Clean the outer fork tube[2], then install your new oil seal[5], oil seal clip[4], and dust seal[6].



20. Clean the inner tube[7]. Lubricate the newly installed seals with a light oil and slide the inner tube[7] into the outer fork tube[2].



From here, you'll just need to reverse the process to finish reassembling the fork assembly.

If you discover the taper spindle[9] has fallen out while working with the shock, don't panic. Hold the tube at a slight angle and slide it back down the tube. As illustrated, the tapered end faces up and fits into a boss at the end of the outer fork tube[2]. After you get it facing right-side up, push it into the boss with a long dowel. Also, when you're replacing the fork springs[11], you'll notice there's a difference in spring pitch, i.e. one end is wound tighter than the other. This tighter wound end faces up or goes in last. (Unfortunately, I forgot to take a picture of it.)

As you're reassembling the shock, you'll need to put oil in it. This should be done before you slide the fork spring[11] back in after it has been remounted on the bike. On my '81 Maxim, the factory service manual calls out for 262cc (9.24 oz) of Yamaha Fork Oil 10wt or equivalent. On later models, I presume with air-assist, the factory service manual says to use 278cc (9.4 oz) of oil. I used Castrol 10wt Non-Detergent in mine. Also, if you do have air-assist, the factory service manual says to fill with, but not to exceed, 1.2 kg/cm² (17 psi) of air using a manual air pump. Of course, you'll want to adjust this air pressure to suit your riding style.

Hopefully, I didn't miss anything in the directions as there were quite a number of steps. If you see a mistake or something I've left out, let me know about it so I can correct it.

That's about it. Good luck!

 

Looks good, although I might have specified the model/engine size in the thread title. I was wondering at first why you had to remove the handlebars...

 

Looks like the 81 XJ650 and the bar was in the way of using the clamp to compress and get that Circlip out I believe.

 

That's exactly the case. Here's the question that matters: are the actual shock tear down directions correct, or are there different types of shocks that require different steps? Perhaps I need to pare down my directions, focusing just on the shocks themselves.

 

nice write-up Gamuru, may i add a lesson learned the hard way
after adding the oil and before putting the springs in, work the wheel up and down a bit to get any trapped air out
the spring takes up a lot of volume in the inner tube, and the oil and spring better fit or it makes a big mess
this didn't happen on a XJ, but i do it anyhow
oh, and please don't strip the drain screws

 

They may be correct for your 650; the 750 doesn't require the handlebars to be removed. I pulled my fork tubes and did everything on the shop bench; it's been a while since I did them, but I don't remember compressing the springs being necessary.

 

This is probably pretty obvious but I gotta ask.

The ass'y diagram does NOT indicate any bushing/bearing/metal slide.
(Those are the same things, just called diffrent names)

Without those bushings I BET it is alot easier to get those oil seals seated.

 

Wouldn't the whole process be easier if you just removed the forks from the triple trees first, and then disassembled? That's what I always do - that way you don't have to bother with removing the bars at all.

 

I've edited the instructions with your suggestions. See the paragraph before Step 7.

I'm not following you. I hate to sound ignorant, but I really don't know what youre talking about. Which bike did you find this "bushing/bearing/metal slide" thing on?

 

Most forks I've worked on have copper bushes below the seals and at the bottom of the stanchions. Although your bike doesn't (?).

Also, another tip with disassembly is to put the complete fork horizontal in a vise (grip the caliper / axle mounts) and undo the damper rod bolt. The pressure from the springs will hold the damper rod in place (no need to use that "special tool"). Then stand the fork up in a bucket to allow them to drain (go grab a cup of tea). Put the leg back in the vise, remove the dust seal and circlip, then pull the stanchion out of the fork leg.

BTW - nice write up. The pics make it easy to follow 8)

 

I have changed the fork seals in a number of bikes, including both my Maxim X's by simply drilling and screwing a self tapper into each side of the old seal, clamping the screws in a vice grip and tapping upwards. No dismantling required, takes about 2 hours for both sides and you are back on the road. You need a Dremel of course to do this.

I also tried the dismantling route, just for comparison - no advantage to dismantling IMO.

 

This is on the 82 750 seca. The haynes calls it a bushing, bike bandit calls it a metal slide(trust me I had to order one), and the guy who helped my remove a stuck bushing called it a bearing.
So as of right now I am calling it a bush-bear-a-slide

 

Wow! I just looked up that bike (XJ750RJ) in the Yamaha Online Parts Catalogue. There's a lot more parts involved than what I've got.

Hmmm... I may need to specify, as schmuckaholic suggested, which bike(s) this applies to.

 

The biggest problem with not dismantling a fork with a blown seal is that you won't be able to clean the crap out of the inside of it. Once the seal starts to leak the remaining fork oil will get quickly get contaminated with dirt - and this will shorten the life of the new seal if it is not removed.

Plus using self tapping screws is just dodgy 8O

 

hey gamaru, or anyone else for that matter... I cant seem to get the circlip under the top cap (by the air valve) out... do you have any suggestions on getting that bugger out? tools? method? thanks! PS.. cant find the vise in all my moving boxes (just moved this wkend), so im using a friend to push down... will this present a problem? THANKS!

 

Truth be told, that little circlip about kicked my butt, too. I finally found and used an old anti-rattle clip from a brake job. I bent a small hook in it which allowed me to slide it under the circlip so I could ease it out of the hole. It about gave me fits. After I pushed the cap bolt pushed down, I shoved the circlip down into the newly made space. Then I slid the anti-rattle clip under it and slide it back up past the groove. Once I made it past the groove, I was able to pull it out of the hole.

Just make sure that, once ejected, no one gets hit in the eye by flying parts.

 

thansk!

 

i get to do this shortly..

the oil leaks out like a... i don't have a cool saying for it. sorry.

It's just leaky.. leaky over my forks, breaks, tires, fairings...

 

I removed each fork. Placed it on the ground while keeping it upright.

Take a half inch socket wrench with a 9" extention. Put this set up between the "top plug" and sholder. Apply pressure from sholder, and use both "free" hands to manuveur some electrical screwdrivers.

Not the easiest way, but it is still a way to remove that circlip.

Gamuru you are 100% correct by saying "Watch for flying parts"
For the obvious safety reasons, but also that clip can go flying.
The plug has also been know to go skyward from the spring pressure.
Not nessisarily at a dangerous velocity, but just enough to go rolling under the frig :roll:

 

BTW, the 1985 is way different. I did mine today and had a supper easy time of it. No circlips (I hope!) among other things. I wish I had taken pictures. Thanks for the write up, it totally got me headed in the right direction!