I'm hearing a new noise. It's sort of a random occasional clatter - not a regular steady rattling, just a single thin metallic clank now and again. It sounds like I think it should when the chain strikes the chain guard or some other part - and in fact, I suspect the chain.
I seem to hear it when I'm shifting, or when I'm cruising at a steady speed on and off the throttle where the engine is on the edge of pushing the bike, or going down a slight incline - in other words, when the top run of the chain isn't under strain and could be bouncing or oscillating. Does this sound feasible? It's not too loud - I just can't pinpoint the noise over the engine and wind noise from inside my helmet.
I checked my chain's adjustment, and it hasn't changed from where I last left it, just over 1-1/2 inches play at rest. I cannot push the chain sideways and make it contact the chain guard. The upper run of my chain passes over some frame structure at the swing arm bushing, just behind the "chrome" cap and beneath the brake light switch. At rest, the chain is 1/8" above the frame at that point, and it takes very little downward force on the chain to make it contact the frame. In fact, I'm surprised I haven't noticed this earlier, and I'm surprised that the chain is meant to run this close to the frame. I haven't yet run it stationary, in gear, on the center stand to try to duplicate it. FYI, I have 1361 miles on the OEM chain, and I've moved the adjusters 4 notches since new.
I've tried hard to photograph it, but I just can't get in there. I am posting two photos, taken from above the foot brake lever toward the back - I've moved the brake light switch spring out of the way. The first is a wide shot just to show the area in question, the second is a crummy closeup of the chain hovering over the frame part.
Any thoughts or suggestions? As you can see, I'm fixating on the chain, since I can't think what else it might be, and I'm hoping that a chain problem is an easy one to fix?