BMW F 650 GS: Replacing the chain and sprockets

This procedure applies to F 650 GS BMW motorcycles, with or without ABS, model years 2005-07.
Do not attempt any of these procedures unless you're confident in your skills - however limited - as a shade-tree mechanic. Don't send me hate mail if you mess something up!!

Replacing the drive chain and both sprockets

NOTE: BMW's shop manual specifies that you remove the swingarm to replace the chain. Unless you're fitting an endless chain, DO NOT REMOVE THE SWINGARM!!

Put the bike up on its center stand and SECURE it by running a tie-down through the front wheel and around the center stand legs. Remove the side cases if so equipped. Make sure the bike's rear wheel is completely off the ground.

This isn't a complicated process, but you do want to be methodical about it.

  1. Remove the chain guard - the whole thing, not just the little cap that goes across the rear tire. There's 5 screws - 4 you can see easily and one underneath the swingarm. (Torx T30) (see Images 3, 5 - Note on these images: in the photos, it says T25 for the chain guard screws. THIS IS INCORRECT! Correct driver is T30)
  2. Remove the front sprocket cover - 3 bolts (Torx T30) (see Image 1)
  3. Run the chain adjusters all the way slack (Torx T45) (see Image 4)
  4. Loosen the rear axle nut (19mm on one side, 24mm on the other) (see Images 3, 5)
  5. Flatten out the existing countershaft lock washer (hammer & chisel) - gently, but don't sweat it too much. You're replacing these parts and the sprocket, so don't worry about damaging them. (see Image 2)
  6. Put the bike in gear and have your lovely assistant push down as hard as possible on the rear brake pedal.
  7. Using the breaker bar and a 30mm socket, loosen the countershaft sprocket nut. It was put on with loc-tite, so it's going to take some muscle. Continue loosening it until you can turn it with just your fingers. (see Image 2)
  8. Now, BMW suggests that you remove the swingarm to replace the chain, but that's because the replacement chain they specify is endless. Screw that, you bought a nice 520 DID X-ring aftermarket chain, so you're not removing the swingarm.
  9. Using your chain breaker, "break" the chain and remove it.
  10. Remove the rear axle nut (see Image 3), then pull or drive out the rear axle. Be sure to support the wheel while you're doing it. The brake caliper "floats" on the swingarm, so it won't come off.
  11. Lay the rear wheel brake disc side down on something to support it so the disc doesn't bang on the ground. I like to use a rear tire.
  12. Use a criss-cross pattern and loosen the rear sprocket bolts - 13mm socket on top, 13mm wrench on the pinch nut on the bottom. (You can see the tops of the sprocket bolts in Images 3 and 4.) Once they're all loose, remove them completely.
  13. Install your new rear sprocket by first putting the nuts on finger tight, then use your socket & wrench to snug them down in a criss-cross pattern. Once they're all snug, tighten them to 21 Nm (16 ft-lbs) with your torque wrench.
  14. Remove the ABS sensor (10mm driver) - pay attention to the location of the washer - and spread out the rear brake pads in the caliper.
  15. The spacer that fell off the rear wheel when you took it off goes on the brake disc side of the wheel. Lightly lubricate it with moly paste and maneuver the wheel into position. Have your lovely assistant help you or use a piece of wood under the tire to help. Reinstall the rear axle (lightly greased if you like) and finger tighten the axle nut.
  16. Push the rear wheel as far forward as you can (you may need to loosen the adjusters).
  17. Remove the countershaft sprocket, clean the splines and lightly lubricate them with moly paste. Install the new countershaft sprocket so you can see the tooth count. Put the lock washer in place and finger tighten the big nut. Be sure the lock washer is fully flat against the face of the sprocket. You may need to wiggle it a bit to get it seated.
  18. Install the new chain. I recommend riveted master links, but if you like clip-type master links, then use that. Just follow the chain's instructions.
  19. Once the chain is on, you can tighten the countershaft sprocket nut. Remove the nut and put 1-2 drops of blue loc-tite on the countershaft threads. Being sure the lock washer is properly positioned, tighten the sprocket nut as much as you can with your hands. Have your lovely assistant press as hard as possible on the rear brake pedal and tighten the sprocket nut to 140 Nm (103 ft-lbs) with a torque wrench. (see Image 2)
  20. Properly adjust the rear wheel so the chain has 35-45mm of slack on the bottom run and tighten the rear axle nut to 100 Nm (74 ft-lbs) of torque.
  21. Reinstall the ABS sensor.
  22. Test ride the bike. Check the master link when you're done.
  23. Reinstall the front sprocket cover and chain guard.
  24. Check, clean, lubricate and adjust the chain as necessary after about 200 miles of riding. After that, you should check, clean, lubricate and adjust the chain (as necessary) about every 500 miles or so. The better you take care of your chain, the longer it will last. The sprockets, too.


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