Mystery Tapping Sound

jacMA

jacMA

Joined
Dec 30, 2022
Messages
21
Age
60
Location
Boston
Bike
2000 ST1100
I was winterizing my 2001 ST1100 today - just putting in fuel stabilizer and running it for a bit on the center stand to circulate. When I revved the bike, just a slow up, I heard one tap, no more. If I revved higher, no tap, if I stayed at the rpm where I heard the one tap, no more taps. Maybe a little less than "mostly" repeatable. I was trying to isolate whether I thought it was coming from the valves, driveshaft (the rear does turn a bit on center stand), trans, etc. It "seemed" to be at the bottom of the engine, but I can't be sure. I change the oil and filter every year, and I did a driveshaft fluid change last year - just FYI.

I planned on a valve check over the winter.

I'd appreciate any ideas, or things to check.
 
Try the same action without the engine running. Eliminate the cable / pulleys as a source of the noise.
Also check things like the exhaust outlet bolts and clamp bolts. It could be that something is moving slightly at the first significant change of revs or first sudden change of heat in the exhaust - I'm thinking of the expanion creaks in our pipes and radiator mounts at home when the central heating kicks in.

Sorry - nothing more sensible / hi-tech mechanical springs to mind.

Oh - just spotted - its an 1100. Check the exhaust heat shields at the front 180 degree bend. They are bolted on near the outlet manifolds and in2 or 3 other places. They are known to crack and eventually break off - when they rattle like what I imagine to be a cam belt pulley wheel at about 2000rpm. You could have the start of a crack in one of them. You cannot really see them without taking the fairing off - but you can reach up and twang them. When broken the sound is very obvious. You might be able to get a sound that sounds like it might be cracked - compare both sides.
 
John, I'll check those out. I did just have some of the fairings off chasing a coolant leak and didn't notice anything loose, but then again, I wasn't looking.
 
I had a circular crack in one of mine - the bolt was holding a circle of shield in place but the shield itself - now with a big hole where the bolt had been - was free to vibrate. I 'bodged' a repair with two large 'penny' washers with small bolt holes. One washer on each side. I probably had to use a new longer bolt - I don't remember. This repair lasted for as long as the bike.

If removing the shield - make sure that you soak the bolts in plenty penetrative fluid and leave for a good while to let it do its stuff - the bolts are small and will be rusted and will likely snap off. A tip I obtained from Larry for all tight bolts. Don't keep adding force to undo a stubborn bolt. Keep the same force (perhaps a little more than tightening force) applied for longer - eg a minute. The bolt eventually yields.
 
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Good advice about the heat shields. Think i have had to do that repair once on my 2000 model. Just a reminder your bike is 20 plus years old and it is normal to hear noise like creaks and occasional pops. Mine does it too. just remember old bikes are like old people we make noises too:rofl1:
 
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