Hello everyone.
Today I'm showing how to adjust a motorcycle chain, using my G650GS as the example.
When I'm driving my car and a motorcycle overtakes me, for some reason I always look at its tyres (pressure) and its chain.
As for tyres, small scooters in particular often have squashed-looking tyres, and I wonder whether the pressure is OK.
As for chains, some bikes have chains flapping up and down, and I wonder whether the chain might come off.
So what about my own bike? I fitted a 360-degree camera to the bike, recorded the chain while riding, and watched it myself.
Sure enough, the chain on my own bike (G650GS) was flapping too...
"This won't do," I thought, and decided to adjust the chain. That's the background to this post.
Come to think of it, I had ridden more than 200 km since fitting a new chain, so perhaps it was the initial stretch of a new chain.
I measure the chain slack with a calliper. With this method, though, you need to subtract the chain's thickness (?) from the reading.
Here is how the repair manual says to measure chain slack.
(Drawing: BMW G650GS repair manual, how to measure chain slack. Not reproduced here.)
According to the repair manual, chain slack should be 35 to 45 mm with the bike on its centre stand.
Mine was within spec.
Still, I'll use this chance to go over how to adjust chain tension.
First, loosen the rear axle. (I forgot to take a photo, so the photo above was taken when tightening it. You can see the torque wrench.)
On the G650GS, the axle is loosened with 19 mm and 24 mm sockets.
Use these to loosen the axle.
Once the axle nut is loose, adjust with the tension bolts.
These are Torx bolts. The tightening torque is 10 Nm (from the repair manual).
When adjusting with the tension bolts, check that the scales on both sides of the swingarm read the same, so the wheel is aligned correctly.
When the adjustment is done, tighten the axle nut to the specified torque (100 Nm) and you're finished.
One point to watch: when tightening the axle nut, make sure the scale you just checked doesn't move.
After tightening the axle nut, always check that the scale hasn't moved!
I put a mark on the axle nut, as in the photo above, so that I can tell if it comes loose.
Here's how I fitted the new chain on my G650GS: