Ok, so you want to change your own fork seal, do ya? Since most Kawasaki upside down forks are essentially the same, we will just make this post for all Kawasaki upside down forks regardless whether it?s a 125, 250, or 500. Before you begin, remove the front wheel from the bike, and remove the forks. If you cannot accomplish this without instructions, you might want to consider taking this entire project to a local shop. (I might have a few extra steps here, or might have missed a small step, but remember, I?m doing this from memory, so just post up your questions and we can get you on the right track)
Things you need:
1. Fork Oil ? Two 32 OZ bottles will be necessary (depending upon your fork height and year of bike), and you will have plenty of fork oil left. I use BelRay 5wt Fork Oil. I have also used Red Line oil, but this has become too tough to find locally, so just returned to BelRay.
2. Syringe ? You will need some way to set your fork height. A simple way is to visit the local Ag Supply store and purchase a medium syringe and about 1 ? feet of clear hose that will fit on the end of the syringe. To make your fork level setting tool, simply zipty a length of wire to the end of the clear tube to hold the tube straight. To set the oil height inside the fork, just stick the tube down inside the fork, holding the tube at the desired level even with the top of the fork tube, and have a friend pull the plunger on the syringe. All oil above your desired height will be sucked into the syringe.
3. Disposable blue shop towels. One roll should be just dandy.
4. 14mm ? drive hex tool. This tool is required to remove the valve from the bottom of the fork. Unfortunately, on newer forks, there is a washer under the spring that can keep you from getting all of the old oil out of the fork from the top only, so you really need to remove the bottom valve to do this job right. Make sure to check your valve to make sure it is a 14mm. You can use an old bolt as your test tool before you make the purchase.
5. ? inch drive impact.
6. Empty coffee can for old oil. Of course, you could make a drain pan like the one I have posted in the gallery. This makes servicing forks, shocks, brake calipers, and anything else that makes a mess much more enjoyable.
7. Two new plastic sandwich bags.
Disassembly:
1. Spread several shop towels on the back of your bench on which you will lay parts as you remove them from the fork. Remember, dirt is the enemy, so good clean shop towels are imperative.
2. Clean the outside of the fork with a clean wet rag to remove any dirt or dust.
3. Remove the plastic fork guard if you have not already done so. Place this off to the side, not on your clean rags on the back of the bench.
4. Flip the fork upside down, resting the top of the fork on the ground so you are looking at the bottom of the fork.
5. Install the 14mm hex tool on your ? impact, place the 14mm tool into the valve, and unscrew the valve. You will have to spin the valve faster than the inner fork tube spins to get it out, so this may take a few tries. I have tried to use a 3/8 drive impact, and it simply will not spin the valve fast enough to get the valve to back out.
6. Once the valve comes out, place it on your clean shop towels.
7. Carefully lift the fork and dump the old oil into the coffee can. Once the valve is out, there is not any small parts that will fall into the can, so don?t worry about having to dig something out of the oil later.
8. While holding the fork over the can, pump the fork to pump as much oil as possible out of the fork.
9. Lay the fork on the bench, stuff a few CLEAN shop towels inside the bottom of the fork, and find the right socket for the top cap. This is different for different years, but should be a 14mm, 17mm or 19mm.
10. Place the socket on the impact, lift the top of the fork a little off the bench, and spin the top cap off. Once the cap if out of the top tube, slide the top tube down slightly so access the jamb nut hold the top cap in place.
11. Find the correct wrench for the jamb nut (this can be 14mm, 17mm, or 19mm depending upon year), and snake the wrench between the spring coils onto the nut. Using your impact while hold the nut in place with a wrench, spin the top cap free. Place the cap on your clean shop towels.
12. Remove the spring, and place it on your clean rags.
13. Just under the cap is a small piece inside the small tube on which the cap screws. Look at the way this part goes in while you are removing it, as some of these are installed only one way. (If you forget to look at the way this piece goes in, do not distress. You have a completely assembled fork still waiting to be serviced. All you have to do is take the other fork apart and pay attention this time J).
14. Lift the fork from the bench, and hold it upside down over the can. A small long tube will fall out. Remove it and place it on the clean shop towels. This tube can be installed either way, so don?t worry about watching how it comes out.
15. While still holding the fork over the can, pump the dampening rod (the thing in the middle of the fork that has a big white or black plastic thing at the top that the spring goes over) to remove all of the oil.
16. Once you have removed as much oil as possible, lay the fork back on the bench. Pull out the inner assembly, and place it on the clean rags.
17. Using a small screwdriver, remove the fork seal dust cover and slide it down the bottom fork tube.
18. Look up inside the upper fork tube, and you will see a black snap ring. Remove this with the same small screwdriver, and pull it off of the fork leg. Place this on your clean shop towels.
19. Grab the top fork tube in one hand, and the bottom fork tube in the other. Collapse the tubes and then pull them apart quickly. This action will cause the bushing to impact the washer under the seal and pull the seal out. The action is much like a slide hammer, and may take several attempts.
20. Once the fork seal comes out, lay the top fork tube out of the way.
21. You will notice there are two bushings on the bottom fork tube. The top bushing lives in a recessed section on the fork leg, so you will need to spread the bushing just enough to allow it to slip over the lip of the recess. Be very careful, as you can damage this bushing if you spread it too far apart. Fortunately, these are relatively inexpensive (I believe Race Tech still sells these bushings. Place this bushing on the clean rag.
22. Slide the bottom bushing off the fork leg, and place it on the clean rags.
23. Slide the washer, seal, and dust cover off of the fork leg and place them on the clean rags.
24. Now that the fork is disassembled, you should have the following parts:
a. Upper Fork Tube
b. Lower Fork Tube
c. Inner assembly
d. Bottom fork Valve
e. Spring
f. Top Cap
g. Two bushings
h. Larger washer that sits on top of the spring under the cap
i. Large washer that sits on top of the seal
j. Seal
k. Dust cover
l. Long tube
m. Small piece that sits on top of the long tube.
Cleaning
1. Remember, dirt is the enemy, so it?s time to clean everything. I use either lacquer thinner or spray carb cleaner.
2. Clean all of the small parts first, but don?t take the shims off of the valve unless you are revalving the fork. As you clean, use air to flash the cleaner.
3. For the spring, I feed a shop towel through the top spring coil and simply twist the spring to allow the rag to walk down the spring.
4. To clean the fork tube, spray cleaner into the tube to wash out old oil. Feed a shop towel into one end of the fork tube, and push the rag through the tube with the long small tube that was inside your inner fork assembly. Be careful not to scratch the inside of your fork tubes. Repeat this several times with clean rags until the tube is clean. Also, check the outside of the bottom fork leg for any nicks by running your and down the down the fork leg. If you have a nick, use 400 grit sand paper in a circular pattern up and down the fork leg. This will smooth those nicks that can damage your new seal.
5. The bushings need a little special attention if you are going to reuse the old bushings. You will notice that the Teflon on the inside of the bushings may be frayed on the edges. Use a NEW razorblade to trim the edge frays. It is worth noting that it is recommended to replace these bushing when the fraying occurs, but I have used old bushings for years by just cleaning up the frays. Your choice as to replacement.
6. After you old seal is clean, remove both the inner and outer spring from the seal. Install these old springs on the new seal (On the new larger diameter forks, you will only be able to install the inner spring, as the outer spring does not have enough room to accept two springs. This will add pressure to the sealing surface and extend seal change frequency. (As a note, while I change the oil in my forks several time a year, I have not changed seals on my 500 in three years after doubling up the seal springs.)
Assembly
1. Since you have just taken the fork apart, assembly should be rather simple, right?
2. First thing iss to install are the dust cover, seal, washer and bushings onto the bottom fork leg. To do this, cut a large section of corner off of a sandwich bag. Place the corner piece over the bottom fork tube so that it extends below the top recess. The reason for this is to allow your seal to slide past the recessed edges without getting damaged. The sharp edges can nick the fork seal, making this project a practice run. Unfortunately, you will not know the seal is damaged until your first ride, so use the little baggy to add extra assembly protection.
3. Once the bag is over the fork leg, lube the outside of the bag with fork oil. Use plenty of oil to allow the seal to slide easily. First slide on the dust cover and then the oil seal. Remove the baggy and install the washer, large bushing, and finally the last bushing. Place this assembly aside.
4. Using either a hacksaw, reciprocating saw, cutoff tool, metal chop saw, or other similar cutting tool to make a cut through one side of the old seal. This is your seal driver to install your new seal.
5. At this point, you need a friend (my wife is my trusty assistant, with an added benefit of being easy on the eyes) to hold the folk assembly while you drive in the old seal. Slide the top fork tube over the bottom fork tube about half way. Lift the assembly and place it upside down vertically on your bench or better yet, on the floor on top of an old towel to avoid damaging the top tube. Have your assistant hold the inner fork tube to keep it about halfway collapsed. Slide the large bushing inside the upper tube, followed by the washer. (Here is where the instructions move to backyard mechanic instructions, as most of us are not interesting in shelling out the bucks for fork drivers. They can be made from PVC pipe, but in my opinion, takes too long to be worth the trouble)
6. Using a small flat punch, tap the washer at 3, 6, 9, & 12 in an alternating pattern to seat the bushing into its pocket. I drive the bushing in first, but you can also drive the bushing in at the same time as the seal, this is just more difficult. If your friend allows the inner fork tube to drop very much and then pulls up, the bushing will come out again, so your friend?s job is very important. I usually have my wife stand so she is holding the fork tube at waist level to ease the stress on her arms.
7. Slide the seal into its pocket, twist the old seal at the cut and place it on the fork leg above the new seal. The old seal should sit in the same direction as the new seal to you are not contacting the inside edge of the new seal. Slide the old seal on top of the new seal and tap at 3, 6, 9, & 12 in an alternating pattern to drive the new seal in place. You know the new seal is in place when you can install the snap ring.
8. Once the snap ring is in place, slide the dust cover in place, and tap it in place. During this entire process, you MUST BE VERY CAREFUL NOT TO CONTACT THE FORK LEG WITH THE PUNCH!!!
9. You now have the upper & lower tubes assembled, so its time to install the inside fork assembly. Slide this assembly into the top fork tube carefully so not to scratch the inside of the fork tube. Once in place, carefully screw in the bottom valve by hand. DO USE AN IMPACT UNTIL YOU ARE SURE THE VALVE IS PROPERLY THREADED. I install the 14mm hex tool into the valve to help me hand rotate the valve. Once you are sure the valve is properly threaded, use your impact to seat the valve.
10. Flip the assembly over and collapse the forks. It?s now time to add oil.
11. Begin to pour oil into the fork assembly until you are close to the top of the fork. Pull up on the dampening rod until you feel no resistance, and return the rod to the bottom. Repeat this process (adding oil periodically) until there is resistance all the way to the top. You will notice that oil will come out of the dampening rod tube as you pump out the air. This is normal.
12. Once all of the air is out of the fork assembly, it is time to set your oil level. I will assume you have already built your oil height adjustment tool, so measure the tube from the bottom to 4 inches and mark that spot. Some folks will run a little more or less, but four inches is a good standard. Insert the tube into the collapsed fork assembly, holding the tube at the top of the fork leg at your four-inch mark. Have your friend pull the syringe to remove the old oil. Depending upon the size of your syringe, you may have to empty your syringe a time or two. When you are no longer sucking oil, your oil level is set. Install the long small tube along with the little top piece (in the right direction).
13. Pull the dampening rod to full extension, and slide an open-end wrench onto the dampening rod below the plastic spring guide. Slide the spring onto the dampening rod, resting on top of the wrench. Grab the dampening rod below the wrench about 2 inches, pull the wrench out and allow the spring to rest on your fingers. Slide the wrench through the spring coils and put it back in place. Begin to turn the spring and it will lower into place. Once the spring hits bottom, keep turning and compress the spring against the wrench. You will notice the threads for the top cap are now exposed. Install the washer on top of the spring. Leaving the wrench in place, turn the top cap on and tighten the jamb nut (you might need your assistant to help hold one of the wrenches). Turn the spring in the opposite direction to release the pressure on the wrench and remove the wrench.
14. Pull the top tube up to the cap, and screw the cap in place by hand. Do not use an impact to install the top cap, just tighten by hand.
You?re done. Grab the second fork leg and work your magic. As a note, if you are just changing oil, you might have to remove the valve to dump the oil out of the bottom of the fork, but reinstall before you take the top cap off, as you will not need to disassemble your forks for cleaning unless it has been awhile since your last oil change.
Good luck. Feel free to post up any questions.
Rick
