I’m pretty attentive to the sounds coming out of my F650, in spite of the fact that when I’m riding most of what I hear is the wind. Underneath the wind I can hear tires on pavement, chain purring, exhaust note, intake sound, valve train slippity-slick, and the clicking as I change gears. But mostly, it’s the wind.
Ordinary wind noise is one thing, but under certain conditions you can hear some relatively loud snapping and popping around the helmet. All wind. So when I began to hear an occasional clatter in roughly those same conditions, I had a hard time figuring out what was going on.
My response to sound coming out of the bike is pretty subjective anyway. Sometimes I think the engine has something seriously wrong with it, but over time I have concluded it’s just me. For one thing, every Spring I stop wearing the balaclava under my helmet and I can hear a lot better. Or maybe I’m easing the bike into its shelter and I don’t have my helmet on and the sound is reflecting back off the small enclosure with my head at the epicenter. If I’m honest about it, it has probably been making those same noises for 20,000 miles, ever since I bought it.
Except this latest clatter seems new. And although it’s not there all the time, it’s definitely enough to notice.
I had recently lowered the bike, so that was a clue. One person posted that they had a clatter from their lowered F650 and raising it back up made the sound go away. But I like my bike lowered.
I really needed to find out what it was, but the internet wasn’t yielding anything.
Until I got around to wondering if the chain was hitting something. Maybe slapping against the guides. When I Googled that directly, I came up with a whole new set of posts, people with exactly that problem, especially on bikes with large suspension travel.
If you Google “Motorcycle Chain Slapping” and select videos, you can watch your dual sport chain perform some pretty amazing antics. The swing arm has a resilient cushion for the chain to hit, but I think the material is hard enough and tight enough against the metal so that the chain slapping it can produce a loud ringing bang.
To put it more in perspective, it’s like your suspension bottoming out. You don’t like it when it happens, but its not a big problem unless it is happening a lot.
What to do? BMW dealerships have responded by tightening the chain, with varying success. One suggestion was to put a shim between the swing arm and the protector so you have a large length of space between the protector and the swing arm, lessening the slapping on an otherwise hard stackup of material, transmitting less of the slap to the metal. Seems like a good idea. Another approach is to tighten the rear suspension, which effectively raises the bike a little.
In my case, I had been running my chain loose, so I tightened the it to the tight side of the specification. That helped quite a bit.
Also, I had been running my rear suspension with minimum preload, so I increased it about 1 1/2 turns on the knob. That seemed to help also, to the point where I can’t really tell if it is slapping or not.
The issue of chain slapping is a new concept for me and I won’t say that I am completely satisfied with the present much-improved setup, but I am relieved to know what that sound is.
I couldn’t convince myself it was wind noise and I was right.