F650 Fork Maintenance

Original FAQs by Kristian #562, BradG #1002, Scott ID #1244
Please read the Disclaimer before attempting any work in this FAQ.
Last Updated: 21 July 2006, by Winter #1935

For FAQs related to forks, shocks, maintenance and aftermarket options:


One of the most cost effective upgrades for your F650 is an increase in fork oil weight. This FAQ has been combined from several other FAQs to help you deal with everything from busted fork seals to changing the fork oil.

Oil volumes (per fork leg) for OEM Springs
Bike Oil change (Imp / US pints) Refill after disassembly (Imp / US pints)
Classic F 600ml (1.056 / 1.268) ?
Classic F (lowered) 650ml (1.144 / 1.374) ?
GS 600ml (1.056 / 1.268) 610ml (1.074 / 1.290)
GSL 610ml (1.074 / 1.290) 620ml (1.091 / 1.311)
Dakar 550ml (0.968 / 1.163) 560ml (0.986 / 1.184)
Note 1: Some aftermarket springs may require more or less fork oil.
Note 2: This is per leg, so you need twice as much oil for a complete oil change!
Refill oil weight
Stock fork oil weight is 7.5wt. See also Different Oil Weights
Warning: Don't use a sharp screwdriver!
Rather than using screwdrivers to remove retaining clips and seals and such, I've found a lot of tool supply places sell surplus medical hand tools that work great for such jobs. Dental picks and hemostats are a lot more precise and have a lot less risks of damaging parts than screwdrivers. Believe me I know. And if possible, make sure your getting SURPLUS medical tools, not cheap new imitations. Used stuff from Germany and Sweden is the best, followed by USA. The new cheap stuff from India and Russia are the worst. They will do the jobs, but the metalurgy is nowhere near as good. (meaning, in essence, you can lock the jaws on a 4mm bolt then use them to remove a sliver with a good pair of hemo's. Not so with a cheap set, the jaws will be bent). dlearl #476

Fork Oil Change

Originally the ForkOilChangeFAQ...
edited by Kristian #562, for the GS.


The Classic and the Dakar both have a conventional Threaded Fork Cap. As the thread of this cap is clamped by the Upper Fork Clamps, you need to undo the Clamp Bolts first, before undoing the Fork Cap. The GS on the other hand, has a very simple Circlip Arrangement, not a threaded cap. The Manual says you should undo the Upper Fork Clamps, but I have yet to determine WHY, because you do not need to undo these to remove the Fork Cap Plugs on the GS. The GS is very simple to change the Fork Oil on.

You should change your Fork Oil every 20,000km. Many do it once a year or at least once every 2 years.



Important: Wrong Part Number For Drain Plug Crush Washers
Flash#412 Notes: The BMW parts fiche shows the WRONG fork. Therefore, you will get the wrong crush washers. What you WANT is copper washers 6x10 mm, part number 11 14 2 343 240. (These are the same crush washers as the one used for the coolant drain screw when you work on your water pump) Your dealer will try to give you 31 42 2 312 710 which is 8x13 and WRONG. It will not FIT!

BTW you might think we're mistaken in saying "copper washers" for the fork drain bolts, and that yours are aluminium. However the OEM crush washers are copper, they only look aluminium because of the silver spray paint covering the lower fork tubes. I don't know why they'd want to use copper in between steel and aluminium, but whatever!

Note: Reusing Copper crush washers

Copper crush washers become harder over time, and hence it is recommended you change these washers each time you perform an appropriate service. However you can reuse Copper crush washers: In a dark-ish room (i.e. not bright light), heat the crush washer until it starts to glow a dull red. You can either dunk the washer in water or let it cool to room temperature - either cooling method is okay as the heating process is the important part. This process is called Anealing.

The question is are you such a CBOA you will aneal your crush washers, or are you going to go out and buy a box full from your local hardware store for $10?

Caution: Do not use your fingers to hold the Copper, as you are likely to burn yourself.


  1. Put the bike on the centerstand.
  2. You will have to deal with the fork spring preload, so support the bike under the frame with a jack, or from above at the handlebars. Do not try and support the bike off the plastic bash plate. It is not strong enough to hold the weight of the bike. The GS/Dakar Metal Plate is probably OK, IF you put a brick under the right place.
  3. Classics & Dakar: Do one side (i.e. one fork) at a time, first undoing the upper fork clamp bolt (marked yellow), then removing first the cap on top, then the drain plug on the bottom of the fork leg. Use a SIX Sided 17mm Socket or Ring Spanner, not a 12 Point one. When removing the cap keep downward pressure on it until all the threads are undone, then release slowly until the spring relaxes, otherwise you may ruin the threads or the cap may fly out and bonk you on the head. You do NOT need to remove the Metal Spacer Tube underneath the Cap.

    How Much Pressure on the Cap?

    When you take the load off the front wheel their is not a lot of pressure. I was able to push the cap down as i turned. Once you loosen past the o ring you can push it down and see how much pressure there is as it moves the thread gap. You'll be fine (no need for another set of hands). Just press down with one hand while undoing with the other.

    As a first timer beware: You have extremely fine threads, a steel tube, and an aluminum cap. More so on the refit, but be extremely careful with the amount of pressure you put downwards on the cap. It's really easy to bung those threads up in the aluminum cap.

    As for removal, I use a socket on a short ratchet, gently pushing down on the cap as I turn it, adjusting the pressure to feel the least resistance. It's most important as you near the end; the strength of the spring is easy to resist with your hand pressure, but it's also strong enough to push past one thread on the cap and bung up that all-important first thread.

    Thanks to several contributors

    If you use a Socket, I suggest you get one which hasn't got a Bevel at the leading edge, or grind a normal bevelled socket down one mm or so such that the Hex is flush with the bottom of the Socket. (Alternatively track down the nearest Snap-on truck and get a six-point flank drive socket. These have a relief in the corners of the hex so that they rest on the FLATS of the bolt head, not on the corners. They will absolutely remove any hex head fastener, no matter how rounded the corners are. Will probably cost $20, but cheaper than ruining the plug. You may be able to order from www.snapon.com, but would have to pay S&H. Chuck#1124)

    IMPORTANT (Classic Only): If the tree clamp holds the cap and you try and undo the cap BEFORE you under the clamp bolts it you will Round the Cap Bolt., like one of the previous owners of my bike. Undo the Clamp, marked yellow in the Photo, FIRST. Kristian #562.

  4. GS Only: Do one side (i.e. one fork) at a time, first prise off the black Plastic Cap with a fingernail (No Screwdriver needed!). Test the plug with a Thumb first to check the expected resistance. Then using your rounded rod or screwdriver handle, PUSH the exposed plug down as far as it will go and hold it down. Using your extra pair of hands, insert a thin screwdriver behind the spring-wire circlip (at the discontinuity in the clip) and use a pair of needle-nosed pliers or a screwdriver to lift the circlip out. GENTLY allow the plug to come up out of the fork until the spring relaxes, then pull it out slowly. You do NOT need to remove the Metal Spacer Tube underneath the plug. Then remove the drain plug on the bottom of the fork leg.
  5. Make sure no oil spills on the Brake Disc or Caliper. Clean it off your wheel and rim. After the oil drains, replace the drain plug bolt, torquing to just 6Nm and using a new crush washer. IMPORTANT: (See note below regarding the Crush Washer).
  6. Slowly pour the measured amount of oil (see table for oil volumes) to the fork.
  7. Classics & Dakar: Replace the cap (using a new O-Ring Seal if necessary). IMPORTANT: Screw it on very VERY carefully by hand first, making sure it starts correctly. If it just starts to Jam, undo it and try again. The pitch of the thread is very fine (1mm) and can easily be ruined by cross-threading it.
  8. Classics & Dakar: Torque the Cap to 25Nm and then torque up the Fork Clamp Bolt, also to 25 Nm.
  9. GS Only: Replace the plug (using a new O-Ring Seal if necessary). Push it in and again, using your rounded rod or screwdriver handle, PUSH the exposed plug down as far as it will go and hold it down. Using your other hand, insert the spring-wire circlip until it clips into place in the groove. Try and align the clip so the discontinuity is at the front, this stops (a little) water sitting in the discontinuity). SLOWLY release the plug and when you are sure the Circlip will hold it, remove the rounded rod or screwdriver handle. Replace the Black Plastic Cap.
  10. Repeat with the other Fork Leg.
  11. Make sure you tighten all Fork Clamp Bolts Classic/Ensure Circlip is Properly Seated and the Fork Caps are secure BEFORE taking out the support.

Important: Fork Leg Cap Upstand

Lowering the Front Forks

Mixing Different Oils To Change Weights

What about using ATF Fluid? What is its (ATF) weight?

by Rand #1111

The following is a message posted to the "TransAlp" list which I also read. I am not an engineer and leave it to others to consider. It seems that Anton (from the TA List) has spent a little time checking out his information and it might be good to include in the Fork FAQ.

ATF Fork Oil

Hmmm... A very interesting question. I searched the web and found the following:

Viscosity requirements for automatic transmission fluids vary with the application. Transmission fluids vary with the application. Transmission fluids in automotive applications are usually multi-viscosity, ranging from SAE 0W-20 to 10W-30, and include viscosity index improvers to allow adequate low-temperature performance. Powershift transmission fluids, on the other hand, are often single grade fluids.


Esso ATF DEXRON-III / MERCON is available in one grade. Compared to SAE 5W-20 engine oils and SAE 75W-80W gear oils, it has about the same high temperature viscosity with approximately a 5C fluidity advantage in the low temperature operating range.

Some additional explanation about the difference between the motor oil and the gear oil viscosity grading systems:

Viscosity is the most important property of a gear lubricant. As with motor oil, the Society of Automotive Engineers (SAE) developed a viscosity grading system for gear lubricants. The SAE system lists requirements for both single and multi-grade lubricants, but does not differentiate between EP and non-EP fluids. Typical SAE gear lubricant grades include SAE 80, 90, 140, 75W, 80W, 75W-90 and 85W-140. Although the grade numbers are larger than those associated with motor oils, gear lubricants are not necessarily heavier. The two separate grading systems are used to minimize confusion between motor oil and gear lubes.

ATF Feedback

WTF! Different Fork Oil Colour in Each Leg?

Typical Query: I've changed yesterday (for the first time since I've got the bike from the previous owner) the telescopic fork oil. Right fork had brownish oil, while the left fork had some greyish oil. The two fluids didn't mix in the pan and they appear to be different. Their quantity was around 600ml x 2, so basically correct. Any thoughts? It seems so unlikely that they used two different fluids, one for each fork?

Answer: Various manufacturers use different colors to denote different weights. The last time I changed my fork oil in my F650, I used red Honda 10 weight in one fork and green Spectro 10 weight in the other fork. I was just cleaning out my stock of fork oil. As long as both oils are the same weight and you do not mix them, I am not concerned about who makes the oil. All brand name fork oils are just fine. I always liked Kal Gard fork oil, but it is very black, having MoS2 suspended in the oil and looks dirty when first installed, so most dealers don't carry it. Now that you have replaced the oil with new, don't worry, be happy. Richard #230

Thanks to El Hombre Sin Nombre, Rag#14, Flash #412, Todd #389.

What do I do if I spill fork oil on the brake?

I'm doing my 12K service and changing my fork oil. Of course I would spill fork oil on the bottom part of my brake disc. So I'm gonna go get a can of brake cleaner and spray it good. Is that all there is to it? Citizen

Fork Seal Change

Changing The Fork Seal - Short Version (GS)

by Adamx #1001, 29/11/01

The quick procedure is:

The fork seal kit is BMW part # 31 42 2 312 836. This is the Kit for ONE Seal and ONE Dust Cover. You need TWO seals and TWO dust covers.

  1. Put bike on centre stand & jack bike up so front wheel is just off ground.
  2. Remove the brake calliper and ABS sensor if you have it.
  3. Undo the clamp bolt and axle, slide it out (don't drop the spacer in the dirt), roll out the wheel.
  4. Undo fork clamps & brace.
  5. Slide out leg.
  6. Prise off dust seal and remove the spring clip. 
  7. Prise out the seal. Gentle application of brute force. There's no BMW tool to take 'em out, there is one to put 'em in. Basically, rip it out without scratching the stanchion.
  8. If you don't use the BMW kit, NGK 88-4 41-80 BR20031 is its number. Clean leg, insert seal - use BMW tool to fit. 31 3 620 CE 91 is the tool #. Or you could try using a bit of wood.
  9. Reverse outta there.

Note 1: (24/02/02): As the procedure is almost exactly the same for the GS as for the Classic, particularly once they off the bike.

Note 2: The newer GS fork seals have what look like a spring around the outside of the seal. They are supposed to last longer. Brad, #1002

Changing The Fork Seal - Long Version

Original Classic FAQ by: Spakur, David#476 &
Mal#1011, Photos by Mal#1011.
Additional comments by Pat#1214
edited by Kristian #562

Written from memory and with some help from repair handbooks.

See the Front Wheel Removal FAQ and the Steering Head Bearing Replacement FAQ for for additional information.
For Q & A on Leaking Fork Seals, Dinged Fork Tubes etc, see the Fork Seal FAQ GS Dakar


It is Important to change BOTH of the Fork Seals as soon as you notice that one is leaking, the other will probably soon break. Why? Because the fork oil will probably drip on to the Brake Disc making the Brakes deteriorate (It happened to me after 45.000 KM).

How do you see if the Fork is leaking? Push the forks down a couple of times (use the Front Brake) and look if there is any oil on the Upper Slider - there shouldn't be any. If the Oil has been dripping onto the Brake Disc you'll also have to clean the Brake Disc and the Brake Linings.

How do I clean the Brakes? Do this with some solution (for removing oil) and if that doesn't help use a metal file or some Sandpaper on the brake Linings (not the Brake Disc!) to remove the outer layer (remember that the linings are made of "soft" material that will "suck in" the oil. In the worst case - buy new Brake Linings. This is what I did. Refer the Brake Pad FAQ.


The tools you require as follows (note: while some other bikes require a special tool to hold the damper rod while you undo the bolts in the bottom of each fork leg, the F650 does not need any other tools other than what is mentioned in this FAQ.


BMW Part Number(s) Item
2 x 11 14 2 343 240. Copper Crush Washers 6x10 mm for Fork Oil Drain. (IMPT: See the warning in the Parts for a Fork Oil Change for further info). You MAY be able to re-use the old ones, at a pinch, but they're cheap.
2 x 31 42 2 345 383 O-Ring for Fork Caps. These you can buy generic. Take them to a General Bearing & Seal ring shop and ask for a replacement Oil Sealing O-Ring. You MAY be able to re-use the old ones, at a pinch, but they're cheap.
2 x 31 42 2 312 838 Fork Seals
2 x 31 42 7 681 274 New-style GS fork dust seal - the one with the spring around it
2 x 31 42 2 312 710 Crush Washers. You MAY be able to re-use the old ones, at a pinch, but they're cheap.
Note: Honda Part Numbers

The roads ? of Labrador, NFLD, etc did in one of my fork seals so I checked out the FAQ's and printed the good and proper advice and ordered replacement seals plus a new supply of fork oil. One week later, the day before I should depart for the Jailbreak, still no seals. And I really wanted to ride the F650, although I have several other options. Believing FLASH, as all do, I know that BMW does not mine the ore from which it makes crankshafts, does not make its own seals and bearings, etc. So, I went to the multi far eastern bike dealership and asked for a seal set for my Showa fork. I get H*nda part number 51490-MN8-305 and it is the exact duplicate of the seal and dust cover that I have removed. All a few miles from my house instead of 270 miles like to "my" dealer. 'Hope this may help someone. Regards, Ike647 '97 F650

BMW FORK SEAL KIT FOR A GS: # 31 42 2 312 836
H*nda EQUIVALENT: # 51490-MN8-305 (USD$22 for both seal and dust cap) NothingClever #1441

  • The exact seal dimentions are: 54 x 41 x 11mm. Writing includes... NOK ... 88-4 ... 41-80 ... BR20031 ... 29 ... Flash 412 (C)

  • The fork seals we found here were made by K&S in San Diego. They don't list the F650Gs on teh package, but they are the correct size. Twofingers #1717

Tightening Torques

Classic Torque Values
2# Allen Bolts Front Brake Calliper to Fork leg 32Nm or 50Nm
(check your manual)
4# Clamp Nuts Wheel to Front Axle Clamp 12Nm
1# Front Axle 80Nm
2# Upper Fork Clamp Screws on Fork Bridge
(Holding Triple Tree to Forks), Marked Yellow.
4# Lower Fork Clamp Screws 25Nm
2# Fork Oil Screws (beneath Fork) 6Nm
GS / Dakar Torque Values
Clamps on fork stanchion 21Nm
Sliding tube to bridge 25Nm
Axle 40Nm
Axle lock bolt 20Nm
Callipers 40Nm


Removing the Forks and Springs

  1. The procedure is quite simple and requires few tools. The BMW manual suggests removing the entire front of the bike to do this, but I knew my Steering Head Bearings were good, so I thought that Removing the Gas Tank, Fairing and Triple Tree was just needless work. If you have any doubts about yours, you may as well take it all apart and replace the bearings. Access to the Fork Clamps is a little easier when the Tank (with side fairings) is removed, so you might just want to remove that. If you choose to remove the front fairing, don't forget to loosen the 2 cables to the turn lights and the cable to the headlight. Just squeeze your hand in behind the front fairing when doing this.
  2. First thing is to lift the bike. I bought a motorcycle jack that worked dandy. Available at Costco for $100, it's something I've wanted for quite some time, and this was the perfect rationalization to buy it. It took a couple of tries to get just the right lift, until I found a two by four under the skid plate and the two center stand mounts lifted the bike perfectly straight. I used tie downs to the rear rack and jack and it was extremely stable, allowing me to move the bike around to deal with the limited space I had to work on it, which would have been a problem with the front end removed. That said, I'm sure you could do the jo on the center stand if you wanted. Do not try and support the bike off the plastic bash plate. It is not strong enough to hold the weight of the bike. Take it off if you have to.
  3. Then remove the plastic from the front wheel; the fender and the caliper cover. Then the caliper itself. I made a hook from a clothes hanger bent in the shape of a "C" and hung the caliper from the plastic radiator surround. This keeps it out of your, as well as harms, way. Next was the front tire. Loosen the four bolts on the axle keeper (no need to remove them) and unscrew the axle with the 12 mm Allen wrench Then I removed the fork brace/fender support.
  4. At this point you have the bike suspended in the air with everything removed from the forks, which are now ready to be removed themselves. As stated previously, the manual says the fairing and gas tank (as well as the handlebars on an ST) should be removed, but I found this unnecessary. By simply moving the forks left and right, I was able to get my ratchet in to undo the bolts.
  5. First I loosened the top bolt on each triple clamp, (marked yellow) then I undid the fork cap, taking care to keep the spring pre-load from shooting the cap across the room. You don't need to worry to much about this as there is hardly any pre-load on the stock forks. A word of caution here. The fork caps (17mm) are aluminum with extremely fine threads. The forks are steel, with a spring pushing up on the cap. In order to keep from damaging the threads, especially the last two or three, it's important to keep downward pressure on the cap as it's unscrewed. I found a closed end wrench worked best for this, keeping downward pressure on the cap with my finger while I re-set the wrench. Remember, you should be able to loosen and tighten this cap by hand once the torque is broken. If it won't, there's a good chance it's cross-threaded, so be careful. Doing it by hand also gives you good feedback on the amount of downward pressure you using.
  6. Once the caps are out, you can remove the spacer, washer, and spring from the fork. Then it's time to drain the forks. Get a container ready and open the 10mm bolt on the back of each fork. The first little bit comes out at a good rate so be careful. (I found a supply of oil absorbent close at hand was invaluable for this entire job, BTW). Let it drip for a while, it will save you cleaning up a mess later on as quite a bit is still in there when it stops flowing. At this point, put the axle back in to keep the forks from turning and undo the bolts in the bottom of each fork leg, which hold the damping rods in place. When undoing only half a turn will do as long as it's broken loose. Leave them is place, just finger tight for now. Now take the axle back out and remove the forks by undoing the two Allen head bolts on the lower triple clamp and carefully sliding the forks out the bottom.
  7. You can now take each fork into the workshop.

Disassembling the forks

  1. Taking them apart allows you to clean them, inspect the bushings and replace the seals. This is accomplished by removing the bolts from the bottom of the forks and turning them upside down. (Undo completely the Screw Holding the Slider at the base of the Lower Fork leg. Here it is removed) The damping rod and top spring should fall out. Then carefully place the lower part of the fork (outer tube) in a vice, and using the upper part (inner tube) as a slide hammer, pull the seal out. In the very bottom of the fork is a cup which goes between the damping rod and the outer tube which is very important. If you elect not to completely disassemble your forks, it is necessary to get this cup in correctly on reassembly. At this point I would lay out all the parts and compare them with an exploded picture of the forks from the manual or parts book, so that you know you have everything and you know where everything goes. This mental picture will help you later on, when putting it all back together.
  2. Dismantle the Outer Forks by starting with the "Dust Seal", using something thin to lift it up, and be careful not to damage it. Underneath is a circlip/snap-ring that you'll have to remove with your circlip pliers. (Note: veggie_deluxe found there was no need for circlip pliers - you can use a small flat screwdriver instead).
    Mal 's Approach
    You have to pull off the slider by the slide hammer method i.e. Because the stanchion bearing/bush is a larger outside diameter than the bore of the slider bearing bush they won't just "pull" apart. The idea is to warm the alloy slider so as to release the bush when the two bushes bang together. The stanchion bush stays in place and the slider bush comes out along with the ring and seal. Mine didn't work like that. The bush stayed part way in the slider. This picture shows the fix. With the stanchion bush removed I used the groove it sits in as an extractor for the slider bush. Let the slider hang at an angle so the groove hooks up behind the stuck bush. A couple of light blows with the rubber hammer and it was out. I hadn't warmed it enough beforehand.
    Spakur 's Approach
    Now is the time to remove the Fork Seal, this is done with the so called slide-hammer technique. When I did it, it was really stuck, so mount it in a vice (use some soft material like rubber or a thick rag between the fork and the vice so you don't damage the fork) and start using the slide-hammer method, which means push the Fork all the way in and then pull it out as fast/hard as you can (try first to be gentle - but if that doesn't work don't be afraid to use all your strength). If it still is stuck use a blowtorch or something else to heat the outside off the Fork. When you've got the Seal out the rest should follow. Again remember in which order the parts were in. See also this picture of the order. Here is the Lower Fork with Seal Removed.
  3. Check the fork Slider is straight! Here's a bent one off a damaged bike.
  4. Clean the Forks and check the slider for scratches damages (places were oil could leak out).
  5. Take some time for a religious cleaning of all the parts. For the chrome fork tubes carb cleaner and a well worn ScotchBrite pad work well. Interior of the outer tube I used carb cleaner and a Heavy Duty paper towel, but a cotton cloth would work well too.

Reassembling the Forks

  1. Now it's time to re-assemble. Place the damper rod cup into the (immaculately clean) outer tube, the spring over the (equally immaculately clean) damper tube and drop the pair down the (immacul... you get the idea) inner tube.
  2. Then the inner tube goes into the outer tube and with the damper rod fixing bolt on the end of an Allen wrench (T-Handles work the best) fiddle about until you get the threads started and tighten it down. Don't worry about the torque at this point but remember it's only 25Nm so don't make it too tight! Apparently the Classic Manual says 20Nm, if someone can confirm please?
  3. Next open your brand new fork oil bottle (You might consider changing to 10wt from 7.5wt at this stage) and put a little on the top bushing as well as splash a little bit down the outer tube. (Oh yeah, don't forget to replace the drain plug first, DOH!).
  4. Squeeze the bushing lightly and get it started down the outer tube. Now it's time for a Special Tool. You can get one at any M/C shop for $40-$50 or do what I did, get 1 1/2" PVC pipe coupler and grind the center stop out of the ID. This fits over the 41 mm inner tube perfectly. Then simply tap gently with a hammer until the bush is in. For the last little bit put the washer into the tube as well. When the washer has bottomed out you know the bushing is in as far as it will go. (Note: Tempo #1908 states "The suggestion to use a PVC coupler to set the bushing is brilliant. But it's a 1.25" coupler, not 1.5". A 1.5" coupler does not fit in the slider. Fortunately I caught this while I was at the hardware store. I still bought one of each just to verify.") - Ed note: Can someone please confirm the appropriate size?.
  5. Next lube up the INSIDE of the seal with good ole #10. If you get any on the outside wipe it off and slide it down over the inner tube. Make sure the writing on the seal is up and you can see the spring. (another DOH!) Then place the Fork Seal Tool* on top of the seal and tap down gently again until the seal bottoms against the washer.
  6. Fit the seal retaining circlip/snap ring into it's groove using the circlip pliers.
  7. Next lube up the dust cover and press it down firmly over the top of the seal/seal retaining clip.
    Mal's approach to make a Drift
    (Fork Seal Tool) to drive the Seal in
    Spakur Notes (Reassembling the Outer Fork)
    • Insert the pieces you removed after the Seal and then put the Seal in. Here is the insertion order on the Stanchion.
    • Don't forget the Damping Guide on the end of the Damper Rod.
    • When inserting the Seal the Professionals use some kind of special tool for this, the tool fits around the fork slider, because they don't want to damage the Fork slider or the Fork Seal.
    • I managed without one, using different hammers/drifts, but be careful not to scratch the Slider or damage the new Seal.
    • I had to use a lot of force to get it all the way in so that the circlip could be fit in its place/hole. The Seal should be fitted evenly!
    Mark #403's Approach
    • I took a 12" long piece of 1.5 inch white (sched 40) pvc pipe, cut it down the length of it, carefully (so as not to burn it) heated it with a propane torch to get it softer, and stretch it open along the cut to fit the 41mm fork tubes. Cold water "locked in" the new diameter.
    • This is now my fork seal driver. worked perfectly and cost about $1. not sure if 2 inch pipe would have worked without modification. I didn't have any on-hand.
    • You can also buy a fork seal driver. once you get the forks off and take them apart, it's pretty easy to see how to replace the seals. However, if you have a leaking seal, you MAY ALSO have a damaged fork tube causing the leak.
  8. You might consider changing the Oil on the bike, but ensure it still on the Jack/Prop. Don't forget to change (and oil) the Top Cap O-ring (if you bought one).
  9. Torque up the bolts in the bottom of each fork leg. With regards to these bolts: Always loosen first and tighten last. That's because the damper assembly/tube it screws into needs the pressure of the main /long spring pressing on it to prevent it turning. When undoing only half a turn will do as long as it's broken loose. The same applies when tightening it. Nip it up to the correct torque when the top cap is screwed down. That means of course the top cap has then got to be removed again for the oil to go in. This can be done before the leg is fitted to the bike.
  10. Change the Oil. See the Fork Oil Section for details of Oil Volumes. Once the oil level is set, it's ready to button up. i.e. Replace the Top Cap.
  11. Reassemble the Forks on the bike. Don't mix up left and right! the forks should stick up 3mm above the Fork Bridge. A note here. Unless you have a lowered bike, when you disassembled your forks the top of the cap was even with top of the top triple clamp. This spec has been changed. The top of the INNER TUBE should protrude 3mm above the top of the triple clamp. 3mm Upstand. At this point I just tightened the two Allen bolts on the lower triple clamp, just enough to keep the fork in place and torque the fork cap and the damping rod keeper bolt. Next I put the fork brace on, then the wheel. Torqued the axle bolt, leaving the pinch bolts just finger tight. Then the top fork pinch bolts, getting the bike off its stand or jack and, I sat on it and compressed the forks several times. This lines up the forks and axle. Then I torqued the lower fork bolts and the axle pinch bolts, then undid and re-torqued the top fork bolts.
  12. Reassemble the Mudguard and the Wheel.
  13. It is also a good idea to check your Steering Head Bearing Play after reinstalling the forks, if you have the Tank off anyway.
  14. Now all that is left is to replace the caliper, caliper cover and the fender. And ride.
  15. Don't forget to squeeze the brake handle a few times after re-installing the wheel to ensure your brakes "take up"!


Spakur: "I think I spent about 10-12 hours working on it, but this was my first mechanical Motorcycle job - done a lot since then - so with the right tools and some experience I'd say about 6 hours to finish it.". Good Luck!


Fork Stanchion Maintenance to Prevent Seals Leaking

Thanks to Marty #436

GS Fork Seals Leaking

by Adamx #1001, November '01

When BMW replaced a first seal for me, the technical explained that there had been a faulty batch worldwide, but the design had been changed to a double lipped type. The original design was used in several different models so not it wasn't just a F650GS problem. Now it appears there may be a second duff batch or maybe a manufacturing fault in the GS legs?

To PREVENT it happening, see the Aftermarket Fork FAQ

Please send us your stories, info, BMW reactions. It's obviously a problem worldwide. Postings below:

Removing and Installing Forks

Problems Removing Forks

jesse has gone through the process of many little problems disassembling the forks... the following questions are based on several threads covering many problems. Note: For details on the procedure to remove and install the forks, see the Fork Seal Change - Procedure.

My Front Axle Will Not Come Out

Loosen the axle clamps first. The axle may also be bent.

I can not get the forks to separate (upper "chrome" slider to separate from lower 'tube')

Tricks to remove the bottom screw of the fork body?

What's the trick to get the bottom screw out of the fork body? I got it to break loose, but now it just spins and won't come all the way out. grofmon #1857

Fork Problems (Q&A)

Why does the F650 NOT have inverted forks?

If all goes well, I should be test ridinga F650 Dakar this Thursday, and placing order subsequently. Beinga dirtbiker, I keep looking at that spindly little set of forks and wondering why on earth you wouldn't put a set of inverted forks on a 400 pound bike. Especially after looking at the brochure with pictures of a guy actually jumping the beast. I have no plans of airing it out, but I'd feel better dropping $9k if it had say 48mm inverts. HomeMadeSin

Why are Inverted Forks Better?

Flash #412, 07-Oct-01

Are the GS and Dakar Forks The Same?

Are the F650 93-94 and Strada -98 forks the same?

Yes. See the Parts Fiches (thanks to Flash #412 and Fede

What can I do about bent or twisted forks?

As a summary, a driver in the small town of Abancay, Peru crashed into our bikes parked on the side of the street (two F650GS/Dakar 2002). The handlebar and the top of the fork are perfectly aligned. The top of the fork and the wheel, however, are no longer at a 90 degrees angle. The fork is twisted by what seems to be a 2 or 3 degrees angle. pierresas

How much does it cost to replace the fork?

How do I know if my forks have been modified?

I've checked the FAQs a few times and am wondering if my forks were modified by the previous owner. Here is the situation: The front wheel hops on relatively smooth road surfaces. It does this constantly, at any speed. The tires are balanced. Over large bumps the fork compresses and absorbs the shock. Small bumps, nada. todd911

GS Catastrophic Fork Failure?

I own a F650 GS that I received new in June of 2000. After about 5,000 miles, I experienced a catastrophic failure of the castings on both side of the front forks. I sustained major injuries. BMW has admitted to knowing of 3 nearly identical failures before they redesigned the forks, adding more material. They decided not to notify owners. I'm wondering if any Chain Gang members know of similar failures. Gertarg '00 F650GS

Fork Seals Stuck?

In the middle of replacing the fork seals, per the FAQ. Now at the point where I guess I am going to have to use HEAT. I think I read Mal to say "warm the slider." and Spakur says "heat the outside of the Fork." Which is it, and where exactly on the fork or slider should the heat be applied? davidbwatkins #651

Fork Seals Not Covered Under Warranty?

The other day, I noted that my Beemer was leaking from the left fork. I logged on here, found out it was common, but since it is an '02, figured I would call the dealer in Denver. I was told that fork seals are not covered under their warranty. I asked why. He said, basically, that it happened so frequently that they chose to exclude them from their coverage. I thought I was hearing things! tannlege

Fork Seals Continually Leaking?

I have been fighting a long running problem with 1 fork seal on my GS. I have been getting about 5000km before it starts to leak, change the seal and the process starts all over again. So, I decided to replace the stanchion(sp?) BMW shreaded my wallet to the tune of A$303 and it came with the sliding bush fitted (thought that would have been an extra!)

I decided to also replace the seal in the other side at the same time. In the process I also decided to try a new fork oil which also shreaded my wallet! Like A$39 for 2 litres. Its Silkolene VI-300 Pro RSF 10 weight, looks purple in colour. is a fortified synthetic oil. This oil appears to have better damping than the ordinary 10 weight I was prev using. I also reused my extra washer spacers to add more pressure to the fork springs than standard, making the bike sit up a little more at the front and give me a little extra travel without bottoming, in bad terrain. An 11pm test ride showed a nice firm, well damped front end with no leaks.......so far! jack

Does fork oil get old?

I know that old brake fluid in an opened container absorbs moisture and is best discarded. But what about fork oil? I have a half-bottle of fork oil. It was opened, then closed about 1.5 years ago. Use it or toss it? Raymo, #1173

I must admit I kinda wish the line "Loosen the axle clamp"
had been in large, bold font in the FAQ.
It woulda made axle removal MUCH easier.
I just thought it was so difficult because maybe it was bent... jesse