I'm not 100%-but apart from that
emm, not sure of your bike, however it sounds like a diaphragm pump, does it sound like a Thuk Thuk Thuk Thuk ?
or,, a Thak Thak Thak Thak ?
go out and have a listen then come back in and tell us which one
yep sounds like its OK, you'd be better checking with a fellow owner on this-the diaphragm may be 'holed' and causing this noise-or maybe its supposed to sound like that ?