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changing fork oil

what you'll need:
Time needed: Give yourself all day if it's your first time. That way you can be pleasantly surprised if you don't have to make three trips to Sears for random stuff. The second time I did this, it took considerably less time -- maybe three or four hours altogether.

  • Parts:
    • 1 liter of fork oil (This is enough for the 2001 SV650S. Check your service manual if you have a different bike.)
    • 2 new oil seals
    • 2 new dust seals if yours are torn (I could reuse mine)
  • Tools:
    • 6mm hex bit
    • 10mm socket
    • 12mm socket
    • 14mm socket
    • 22mm socket
    • small flathead screwdriver
    • impact wrench
    • mallet
    • vise
    • improvised tool #1: extended 8mm hex bit (see below)
      • 8mm allen wrench
      • 8mm socket
      • adapters to fit the 8mm socket onto your impact wrench
    • improvised tool #2: PVC seal driver (see below)
      • 8" long piece of 1.75" inner diameter PVC tubing
      • hose clamp to fit around PVC tube
  • Misc:
    • front stand (or some other way of keeping the front end off the ground)
    • measuring cup
    • plastic cup and a sharpie marker
    • large funnel
    • container for old fork oil -- I use an empty plastic juice container with screw-on lid
    • ruler
    • paper towels and shop rags
    • clean piece of cardboard/rag to lay fork innards onto

reassuring words.
As you can tell from the parts list above, this is a pretty complicated procedure. It's not really all that hard, though, once you get the hang of it. Trust me -- if I didn't spill fork oil all over the garage or break anything in the vise, you'll have no problem at all.

While washing the bike not too long ago, I noticed that my right fork was covered in black gunk. I wiped it off, but found the gunk again the next time I looked. Most likely, some dirt or dust worked its way down past the dust seal and got trapped between the oil seal and the fork leg, allowing fork oil to escape. Another possibility is that the oil seal, after 30k miles of holding back dirt while being subjected to the elements, finally cracked. Either way, I was getting nasty muck all over my fork and nasty muck entering the fork chamber.

This write-up should be applicable whatever your reasons for swapping your fork oil. Many people like to put thicker weight fork oil into their SV immediately upon purchase. I stuck with the stock oil until this service, at which point I put in 10 weight oil. If you're disassembling your forks to cut down the spring, add a longer spacer, or replace the damper rod, merely insert your own steps at the appropriate place.

improvised tool #1
Peter and I had to make two ghetto tools in order to do this procedure. Both worked really well and cost almost nothing.

Improvised tool #1 is an extended 8mm hex bit for the impact wrench. The 8mm hex bolt you'll to remove is recessed into the bottom of the fork, and neither my impact hex bit nor my normal hex bit was long enough to reach. I really don't recommend using the following tool for anything other than removing this one bolt on the fork. Seriously. It's not impact-grade.

Take a long-handled 8mm hex wrench and cut about 2" off the end.

Insert the 2" piece into a normal 8mm socket. Now, use adapters so that the 8mm socket will fit onto your impact wrench. Naturally, I had to use every adapter that I own, and therefore had the 2" hex wrench piece, a 1/4" drive 8mm socket, a 1/4"-3/8" drive adapter, a 3/8"-1/2" drive adapter, and, finally, the 1/2" drive impact wrench. Seriously, kids, this is ghetto. It does work for this application, though.

improvised tool #2
The second ghetto tool is a seal driver. Go to Home Depot and get a piece of 1.75" inner diameter PVC tubing (the outer diameter of the fork is 41mm -- about 1.6"), and about a foot long. Cut a slot in the pipe so that you can stretch or shrink the diameter. Next, slide a hose clamp over the PVC. Voila: Improvised Tool #2.

Put the bike up on a front stand and remove the front wheel.

Remove the front fender.

remove the forks.
Using a 10mm socket, remove the reflectors and speedometer clamp from the front forks.

Use a 6mm hex bit to loosen the pinch bolts on the triple clamp. You don't need to remove these bolts; just loosen them enough so that they turn freely. There are two such bolts: one next to each fork.

Use a 22mm socket to loosen the fork caps. DON'T remove them -- just loosen them up a turn or two while the forks are still held tightly to the bike. You may have to use an impact wrench if your caps are reluctant to turn.

Use a 12mm socket to loosen the two bolts (per fork) on the lower triple clamp. The top one is easier to get to from above; the lower one is easier to get to from below. Be aware that when you loosen the second bolt, the miracle of gravity will cause the fork to drop. Be prepared to catch it.

disassemble the forks.
Now that the forks are off of your bike, it's time to disassemble them and get the old seals out. Go ahead and use your 22mm socket to remove the fork cap. Remember that it has a spring directly under it; it doesn't pop off very far or fast, but it would still be an unpleasant experience to point it at your eye while you unbolt it.

Once the cap is off, you can reach in and pull out the spacer. Put a funnel into your fork oil receptacle, and tip the fork over it to drain the oil -- be careful, though, because a washer and a spring will slide out.

The next thing that you have to do is remove the damper rod bolt at the bottom of the fork. This bolt holds the damper rod, which, amongst other things, holds the inner fork tube onto the outer fork tube. I couldn't see any way to get the old seal out without taking the inner tube out of the outer tube; thus, I needed to remove the damper rod bolt. Keep your funnel/container handy, since more oil will drip out of the fork.

We found that it was pretty much impossible to get this bolt out without using an impact wrench. So, make your life easy and use the impact wrench before trying anything else.

Take the whole fork and clamp it into your vise. Make sure to place your funnel/container underneath the downhill side of the fork, or you'll make a mess.

Use Improvised Tool #1 and the impact wrench to remove the damper rod bolt. If the psi is high enough, and you really give it a good jolt, the bolt should come out pretty quickly.

Next, you're going to remove the dust seal. You can pry this off with a small flathead screwdriver; it's really easy to remove.

Underneath the dust seal, you'll see a metal retainer ring and then the oil seal. You can also use the screwdriver to pry up the retainer ring.

Ewwww, yucky rusty gross old oil seal!

Now, grab the inner tube with one hand and the outer tube with the other. Give it a couple of good tugs until the tubes separate. Be horrified by the toxic sludge that's been living at the bottom of your forks.

Once the tubes are separated, the disgusting old oil seal will slide right off. You can use it to scare children and old ladies.

While you have all the fork innards out, inspect them for damage. Measure the fork spring and make sure it's within spec -- for my 2001 SV650S, the lower limit is 12.25".

reassemble the forks.
Now that you have the forks taken apart, it's time to put them back together! Whee!

Make sure to really clean all of the parts before putting them back into the forks. Dust or dirt in the oil can work its way back up through the oil seal, leaving you right back where you started.

Slide the damper rod back into the inner tube. Make sure that the thick rebounding spring is fitted onto it. If, at any point, a small and thin spring fell out of the fork, that goes onto the tapered end of the damper rod. Make sure that the tapered end of the damper rod falls all the way through the inner tube so that it lines up perfectly inside of the white plastic bit at the bottom of the tube. You want to see the threaded hole here -- this is where the damper rod bolt will attach.

Now, slide your new oil seal onto the inner tube so that it rests above the other metal collars (the little metal retaining spring should be facing up). Once the seal is on, slide the inner tube into the outer tube.

Push that sucker all the way in as far as it'll go. You should end up with the oil seal being just about flush with the outer tube. Slide the dust seal onto the inner tube temporarily (if you bought new dust seals, use the old one for this next part).

Now, go get your Improvised Tool #2 (also known as PVC tube and hose clamp). Slide the PVC tube over the inner tube and tighten the hose clamp so that the PVC fits just above the dust seal. Once it's in place, give the PVC a few really good whacks with the mallet. We found it most effective to give a couple of whacks, turn the PVC tube 90 degrees, give another few whacks, turn the tube, etc etc.

Remove the PVC tube and dust seal. As soon as there's enough room on top of the oil seal for the metal retaining ring, fit that into the little gap. It doesn't matter if it can't seat into its groove yet; you just want it to smoosh into the top of the inner tube, above the oil seal, right now.

Put the PVC tube back on and keep whacking. Once you have the oil seal driven down enough so that the retaining ring is seated into its groove in the inner tube, you know that you're done. At this point, you can slide your dust seal on (use the new one now, if you have it). It'll just push right on.

Now it's time to reinsert the damper rod bolt. Clamp the fork back into the vise. Use a long-handled 8mm hex wrench to thread the bolt into the hole at the bottom of the damper rod. Don't turn it in very far; just enough so that you know you haven't cross-threaded the bolt.

Now use your impact wrench and Improvised Tool #1 to tighten the bolt. The damper rod should stay in place and the bolt should seat fairly quickly. Use Improvised Tool #1 on the end of your torque wrench to tighten the bolt to 30 newton-meters.

adding fork oil.
Each fork for the 2001 SV650S takes 491mL of fork oil. There's an easy way of measuring this without a lot of drama. Go into the kitchen and get a measuring cup and a disposable plastic cup. Pour 491mL of water into the measuring cup, then pour that water into the plastic cup. Take a Sharpie marker and mark the water level on the cup. Pour out the water.

Take your plastic cup out into the garage and fill it to the marker line with new fork oil. Hold the fork upright and put the funnel into the top. Slowly, pour the new fork oil into the top of the inner tube. Once all of the oil is in, slide the inner tube up and down slowly to really work the new oil into the damper rod.

Carefully drop in the spring, washer, and spacer.

Once all the innards are in place, raise the inner tube up so that it (nearly) covers the spacer. Carefully put the fork cap back on just far enough so that it won't pop out. You won't be able to really tighten it. Also, cover your hand with a sleeve, or a rag or something; the top of the fork cap is pretty sharp when you're applying pressure down onto it.

reinstall the forks.
Slide the fork up into the triple clamp and tighten the top pinch bolt. You don't need to torque it; you're just holding the fork in place for the time being. Once the pinch bolt is tight enough to hold the fork up, torque the fork caps to 23 newton-meters.

Loosen up the pinch bolt again (remember your friend Mr. Gravity; be ready to catch the fork). Slide the fork up or down until the distance between the fork cap and top of the triple clamp is 3mm (again, this is for the '01 SVS -- check the service manual for your particular bike). Tighten the pinch bolt again when the fork is in place. Torque the pinch bolt to 23 newton-meters.

The rest of the fork installation is the opposite of the fork removal. Torque the lower fork bolts to 23 newton meters. Replace the reflectors and the speedometer cable clip.

Once the forks are back on the bike, re-install the front fender and the wheel.

To reduce the risk of oil seal damage on my upcoming trip, I also installed a pair of Traxxion fork seal guards. They snap right onto the forks, but to tighten the bolt, you'll need a T-30 Torx wrench.

Incidentally, here in Northern California, most communities have recycling programs that will accept the used fork oil. Every other Thursday, the city comes by for paper/cans/cardboard recycling; if we leave oil out in sealed containers, they'll take it away, too. Definitely recycle the oil if at all possible.