F650GS Fork Oil Change

October 25th, 2008 · Comments

Yesterday my 2003 BMW F650GS Dakar hit 32,778 miles. I had actually hoped to take a photo of the odometer at 32768 (2^15), but failed at having a camera with me at the time. I’m supposed to change the telescopic fork oil every 12,000 miles, but until recently the fork seemed to be fine. Doing fork maintenance on the Dakar is pretty trivial. Once you have the bike up on the centerstand, you loosen the upper fork clamp bolt, then the fork cap:

Then you loosen up the drain bolt on the bottom of the fork legs. Each leg has 550ml that will drain very heavy very fast. I didn’t do so well with the first leg that I drained:

I had actually planned to change the fork oil when I did my 30k maintenance, but I wanted to replace the O-Rings in the fork, and had to wait several weeks for the O-Rings to come in stock. When I got them, they were the wrong ones. The ones on the left are my new ones (31 42 2 345 383, for the regular F650GS), the ones on the right are the ones I took out (31 42 7 660 358, for the Dakar). When I ordered it, I guess I just went by the F650GS fork maintenance FAQ, which didn’t mention any Dakar specific parts. Always check the parts fiche! Being impatient, I re-used the original o-rings, and poured in some clean fork oil.

While the other leg drained, I went ahead and cleaned the chain and adjusted the chain slack. This is one of my least favorite things to do on the bike, since it takes a fair amount of precision to line up both swing-arms exactly.

Putting everything back together is pretty easy, except having to push the fork-cap down while screwing it in, so that it compresses the springs far enough to fit:

In the end, I managed to get about 900ml of fork oil into the bottles, out of the 1100ml of fork oil that I was supposed to have drained out. I figure at least 100ml of it went onto the garage floor, so I’m not too worried.