I posted a while ago that my bike makes a sighing noise periodically when it's just sitting in the garage - even if I've not ridden it for several days. Clearly, it's some kind of gas trying to escape. Comes from the filler cap area. I caught it on video from about halfway through one of the sighs. WTF is this and why is it happening?
I’m coming from an 848. I’d read about the tank deforming. My concern is that this noise is similar and is as a result of pressure build up and the same thing could happen to my monster. No more questions after this one
Haha honestly when I’m in the garage this noise keeps happening every 20-30 seconds and it sounds exactly like the bike is sad and wants to go out to play lol!
Leave the fuel cap open and see if it still happens. If it doesn’t, investigate breather holes or pipes including one possibly trapped after a service?
My old boxer dog did exactly the same when she wanted to go out. Does your bike also have a lead in it's mouth? Anyway, my 2 penneth is temperature fluctuations with your fuel tank causing the air inside to shrink a little when it has cooled. Is this sound in the evening after it's cooled a little? Does it also happen after riding when the bike is cooling and the heat from the engine under the tank has dissapated. I think there will be a vent for this and it may be causing the noise. It could also be after you have ridden it and the fuel level has went down causing a slight vacuum and the tank pulling air in. Open the fuel cap and see if you get a slight "woosh" noise. My car does this when I unscrew the fuel filler cap. In full Magnus Pike mode, get an empty 2ltr Pepsi (other brands are available) plastic bottle, fill it with hot tap water and empty it. Put the cap back on and watch the bottle start to collapse after a short time, as the air in the bottle cools, shrinks and the greater air pressure outside crushes the bottle. It you want to go full nut job, put some Mentos in a bottle of cola.
My 821 does it when i stand the bike upright. We also had a 696 that would do it for an hour or so after riding. I fixed it eventually after Ducati dealer advised that as the fuel cools/heats it expands/contracts and that if one of the two hoses off the filler cap and out the bottom of the tank are blocked it can’t equalise the pressure. They reckoned compressed air but I don’t have it so used contact cleaner. Did the job. I think on the 696 it made a noticeable performance improvement too as the vacuum being created was creating more work for the fuel pump leaving to low/inconsistent fuel pressure.
