Originally Posted by jgiacobbe
Do you end up removing and disassembling the forks or do you siphon the oil out? Never did anything with forks before.
Jeremy, just sticking a long tube down into the forks will allow you to suck out the fluid (siphoning won't work), for sure, but, the suction tube stays inside the internal damper tube. Most/all of the grunge collects on the outside of the damper tube at the base of the slider. You cannot get all of it out by this method.
Pulling the tubes, invert, pump and drain is the only way to get it out.
I wrote the following procedure for the post-95 Concours. The procedure is pretty much the same for your forks, but please note the oil quantities are for that bike. Yours will probably be different.
FORK OIL CHANGE
1. Remove the plastic (not absolutely necessary, but makes it easier to get to the lower fork clamp bolts.
2. Loosen the four (two per side) fork tube pinch bolts on the top clamp + the two (one per side) Allen head handlebar clamp screws. Absolutely necessary to be able to loosen the caps since the pinching action constricts the tube around the fork caps.
3. Back out the preload adjusters to the last ring (or until you feel resistance) and break the top fork cap(s) loose. DO NOT loosen these any more than a couple of turns out, or try and remove the caps now.
3a. Elevate the bike and remove the front wheel. Do not allow the calipers to hang on the brake lines.
4. With the weight of the bike now off of the front suspension, remove the caps from the top of the tubes.
CAUTION: There is some pre-load spring pressure on the cap so be prepared once the threads clear. Remove the springs slowly so they don't pull oil out with them and make a mess.
5. Remove the fender.
6. Loosen the two (2) bottom triple clamp bolts (per side) that secure the tubes.
7. Grasping the tube. Use a back and forth twisting motion while exerting a downward force and work the tube out of the clamps. Repeat for the other side. Pay attention which side is the left and right.
8. Invert the tube and dump the fork oil in a suitable container, pumping the tube/slider to get as much of the yucky oil out as possible.
9. Add a couple hundred cc of low flashpoint solvent (I like kerosene or diesel fuel) per tube, then pump the tube up and down several times to loosen up some the crud in the bottom. Invert the tube and dump the solvent into a suitable container, pumping the tube/slider to get as much out as possible. Repeat this process several times for each tube.
10. Add a couple hundred cc of low weight 'cheap' fork oil to each leg and work the tube up and down. This is to dilute any solvent that be be left in the tube. Invert the tube and dump the fork oil into a suitable container, pumping the tube/slider to get as much out as possible.
11. Reinstall the tubes in the bike tightening the the lower clamp pinch bolts only.
12. Add the fork oil. The rest is pretty much the reverse of removal. Follow the directions in the Manual for the proper torque values.
Fork oil by volume: 379cc per leg (completely dry after full disassembly)
Fork oil by volume: 330cc per leg (changing only)
**Fork oil by level ('94-'up): 171mm from the top of the inner tube with the spring removed and the fork fully compressed
** Best method
NOTE: You have not yet installed the spring(s).
13. Now the fun part..... getting the cap back on. Like all things, there's a procedure that helps.
14. In turn, take each cap and place on the top of the tube it will going in during final assembly. Slowly rotate the cap and determine the point where the threads just begin to grab. Using a magic marker, pencil - something - make a mark on the cap so you can reference it with a fixed spot on the top clamp (the slit in the clamp works). Repeat this for the other cap.
15. The whole reason for this procedure is to help get the cap started when the springs are in place. Trying to push down on the cap (against spring pressure) and turn it to get the threads started (without cross-threading) can be a real PITA.
Another hint would be to use a speed wrench. These make it easy to apply a downward force and turn at the same time.
16. Finally, install the springs and their flat spacers. Position the cap in place so your alignment mark is just to the left of the fixed reference you've established. With a straight downward force, push the threaded portion of the cap into the bore of the tube. Insuring that it is straight, rotate the cap clockwise at least a 1/2 to 3/4 of a turn. The threads should have engaged easily to the point that you didn't even notice. Slowly relax downward pressure to make sure the threads are engaged, and if so, continue tightening the cap. Gorilla tight isn't necessary. Once you tighten the top clamp bolts, the tube will constrict and keep the cap in place.
17. Repeat for the other cap.
18. Replace the front wheel, calipers, and fender. Pump the front brake so the pistons will have moved back out to the disks BEFORE riding.
19. Double check all pinch bolts that secure the fork tubes to the triple clamps.
20. Replace any plastic that was removed.