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Fork oil refresh, spelled out

2288 Views 5 Replies 4 Participants Last post by  Longrifle
The following procedure is a step by step for 2000 M900 Dark with 43mm Showa non adjustable forks.
This procedure is how I refreshed my forks with out the need for a special spring compressor. If you have any thing to add to this let me know.

1. Supported rear of bike with rear stand.
2. Supported front of bike with ratcheting tie down straps from handle bars to ceiling rafters. Or whatever means you have.
3. Measure the distance the forks extends over the triple clamp. AND WRITE IT DOWN.
4. Disconnect speedometer cable from wheel and from console. This is a good time to hang it up and flush it out with WD-40. Place a rag under it and let it drip out.
5. Remove front fender.
6. Remove front brake calipers and then tied them to oil cooler for support. Clean the calipers and replace the brake pads if necessary.
7. Remove front axle nut and drift out axle while supporting wheel.
8. Remove wheel, remove clean and re-lube the speed sensor. This also a good time to check and or replace the front wheel bearings and polish and wax the wheel. You should be finished with you first beer now.
9. Loosen the four allen bolts holding the forks.
10. Carefully twist and lower the forks from the supports so as to not scratch them.
11. Wrap a portion of the larger outer fork tube with duct tape to about ¼ inch in thickness.
12. Firmly secure the duct taped portion in a bench vise. DO NOT CRUSH THE TUBE. The duct tape prevents scratching up the tube and keeps the tube from slipping in the vise.
13. With the tube in the vise loosen the top bolt/cap and place a container under the cap to catch oil.
14. Drain oil out. Finish beer #2
15. Unscrew the allen bolt on the bottom of the fork. This bolt is up inside the fork and maybe difficult to get at. When this bolt is released, all internals parts will slide out. Pay attention to how everything came out to ensure it goes back in correctly.
16. Pump the piston until all the old fluid comes out. Have a large pan handy to catch fluid.
17. Rinse all the parts with kerosene OUTSIDE THE GARAGE and wipe dry.
18. Rinse out the fork tubes with kerosene and ensure all goop and metal shaving are rinsed out. Set out to dry thoroughly,
19. Clean the bottom fork bolt and wrap threads with some Teflon tape.
20. Separate the top cap from the internal plunger tube. I had to lock the top cap in the vise and use a lot of torque to loosen the lock collar bolt (I think that what it is called, if not forgive me).
21. When all parts are dry, drop the spring in the tube with the tighter coil side up.
22. Insert the internals back into the tube and connect them to the bolt from the bottom of the fork and tighten. A good woman should be standing by with a cold one ready to go.
23. Fill the fork with appropriate oil. This time I used PJ1 10W Gold Series oil.
24. Pump the plunger tube until all the air is out and add oil to the desired level.
25. Attach top cap to the plunger rod and tighten.
26. Using a wooden dowel or something similar depress the thin metal internal tube and insert the retainer. (the cupped C shaped washer)
27. Replace the o rings on the top cap and tighten back onto the fork tubes.
28. Put your monster back together. Ensure that the forks height is correct.
29. Finish off your beer and admire your work even though it looks the same.

Best,
Longrifle
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Seems pretty straight forward. But if your not familiar with forks, or not very mechanical, I wouldn't try it.

Forks are very important and putting them together wrong can have catastropic results. You need to measure the fork oil height before you reassemble them.

The fork oil level acts as your last bit of spring travel. The air in the top of the forks is hard to compress and acts like a stiff bump stop as I understand it. You need to measure the oil height to set this correctly. You can't just add a certain amount of oil to each tube as you can't be sure that you get all the oil out of the forks or even the same amount of oil.
It is a good idea to loosen the caps while the forks are still on the bike. This way the bike holds the fork for you instead of the vice.
gkotlin said:
<snip>

The fork oil level acts as your last bit of spring travel. The air in the top of the forks is hard to compress and acts like a stiff bump stop as I understand it. You need to measure the oil height to set this correctly. You can't just add a certain amount of oil to each tube as you can't be sure that you get all the oil out of the forks or even the same amount of oil.
It's exactly the opposite. The air compresses easily. The oil not at all.
But as the air compresses, it gets harder to compress. Acting as a progressive bump stop. It keeps the forks from getting to a point where metal is on metal. But it does so in manner that isn't as harsh as metal on metal contact.
Opps, I did leave out measuring the fork oil. Yes, I measured the fork oil with a MM ruler and a good light.
Secondly, if you can loosen the top cap on the bike, great. I could not because of my brake line positioning.
LR
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