Knocking Sound only when Warm

[michaelbryant]

I have been through all the threads here about engine noise. But still I have to be sure and ask specifically:

On my new-to-me ST1100 (2000), I get a tapping or knocking sound when warm--is this "normal", as in can
I just accept it as a natural part of the sound of the ST's engine? Or is this probably a carb-sync issue which
needs to be addressed right away?

At start-up all is well, it only begins after I've heated it up good
in traffic, and come to a stop--then I hear it. It can be quite loud (to me--paranoia?).

I will be at WeSToc in June, so I will have lots of feedback then,
but in the mean time, is it ok to keep on riding and loving my new ST,
or is it important to get a carb-sync right away?

And how much should I expect to pay for a carb-sync by my mechanic?

Thanks for any advice, really appreciated to ease my worries...
Michael

 

[DonMac]

A carb sync is quite easy if a flow meter is used and will take longer to get both side panels, shelter cover and air cleaner out of the way than to do the sync itself. It is not difficult but I was lucky and had an expert show me how to do it. Find someone to do it for you the first time. Shouldn't take long at all.

 

[michaelbryant]

Have you checked the valve clearances ?

My 1100 used to make tick-ticking noises, which disappeared once it was properly warm. I could also tell when the oil wasn't up to the top mark from the way the engine sounded, and using fully synth oil made quite a difference too.

Failing that, I found the best way to make your own bike sound really good is to take your helmet off and listen to someone else ride it. All the odd sounds that you hear when its your bike and you are astride it disappear, and it sounds just as good as every other pan that you ever hear gliding smoothly past.

Thank you, John, I will get the valve clearances checked, and the carb sync...
the funny little noises we hear are always worrisome, but I'm sure half are in our heads (or helmets!)...
and congratulations on being MOTM! A great little write-up you did about your motorcycling times, enjoyed it very much. Cheers

 

[ST1100Y]

I also have a 2000 model with a similar 'issue'... when the engine is really hot after having seen some 'action' (like after rushing up a twisty mountain pass), a silent but significant, low frequent 'stomp' occurs in idle... most mechs don't even hear it, I do though... and it origins from way down low in the engine. I doubt the main bearings as culprit, as those would have failed massively over the years by now (yep, its persistent since quite some time...), but a theory about the crank sided timing belt pulley having a slight clearance showing only on a warm engine could be it (will remove it during t/belt replacement and apply some Loctite on the shaft's dovetailing). Other source could be the clutch, but I've already removed and checked everything in there, without any diagnosis...

 

[BakerBoy]

My 98 had that sound, and I've heard it on others. You get so tuned in that it becomes 'loud' to you, at least it did to me. I've heard some comments here that some think it is associated with the PAIR system. You likely have nothing to worry about, but a carb synch could help a bit.

 

[ST1100Y]

...but a carb synch could help a bit.

Carb sync is dead on (OptiMate digital vac meter, bars are completely steady across all rpm...); raise idle to >1200 and the 'stomp' is gone...