Lately I’ve been hearing a buzzing sound between 2-3000rpm while riding my Himalayan. It’s been getting gradually worse, and I’m using the bike every day to go to work. At first I thought it was the new windscreen I fitted- it’s off a later model, and I had to bodge a bracket from a bit of aluminium. However, grabbing the windscreen while riding made no difference to the noise. Further investigation showed I couldn’t replicate the noise with the bike in neutral, so I started thinking it might be the front sprocket, which I know is worn. I’ve got a new chain and sprockets on order.
The other night, night on my way to work, I started really worrying about it. What if it’s not the sprocket, I wonder? What else could it be? Is there an issue with the engine? I arrive at work and forget about it for the night. It ends up being a late one, and I leave work at 5 am. On the way home, the noise suddenly gets much worse. Bloody hell, it’s the camchain, I think. I’ve knackered something when I put the new cam in. Maybe I didn’t tighten the bolts on the camchain sprocket properly? Perhaps I shouldn’t have reused that tab washer? Or perhaps I’ve installed the camchain tensioner incorrectly? Images flash into my mind of the camchain flapping around, slipping a couple of teeth, a valve hitting a piston. The rear wheel would probably lock up as the engine seizes, and if I don’t pull the clutch in quick enough, I’ll finally get to try out my airbag vest. Assuming the best, I’ll be stuck on the M60 just before rush hour.
Gingerly, I ride the rest of the way home trying to avoid the rpm range where the buzzing occurs. It’s too early to have a good listen to the engine while stationary, I don’t want to wake up the neighbours, so I put the bike in the garage and go to bed. In the afternoon, I do a bit of online research, which seems to confirm my fears. I get the tools out, and am just about to take the camchain tensioner off, resigned to the idea that I’ll probably having to remove the tank and cylinder head too, when I think why not put the bike on the centre stand, run it in gear, and have another listen? I wheel the bike out of the garage, put it on the centre stand, start it and put it in second gear. The noise is there, really loud without a slipstream muffling it. I take the bike out of gear, and the noise continues- for the first time, it’s also there with the bike running in neutral, so it’s definitely not the sprocket. Being able to listen to the noise from different directions rather than from the saddle while riding, it soon becomes obvious that the buzzing isn’t coming from the engine, but somewhere around the headstock. I try pressing the clocks, pulling the windscreen, but the noise is still there. Frustrated, I ask my wife to come out and have a listen. After a few seconds, she grabs the phone mount, and the noise stops. It seems an harmonic vibration was turning the phone mount into a tuning fork, but without any visible vibration. Relieved, and feeling rather stupid, I push the bike back into the garage. Thoughts turn to the Harley, which needs a service, and the rear caliper needs looking at, the pads aren’t wearing evenly. I’m sure the gearbox sounded a bit noisier than usual last time I rode it, too…..I wonder what that could be?