Strange Sound When Idling Daytona 955i

Hello all,
I am getting a strange sound when bike is idling 955i Daytona 1999 model, its a rhythmic Pifthh sound on a regular basis sounds like a pressure relief or valve venting everyone second or so .

I have added a link from facebook from another guy experiencing the same issue hope he doesn't mind .

Any ideas greatly appreciated.

://www.facebook.com/1597521303/videos/312174150753026/

 

yes does sound like that or something like will be checking it out at the weekend