The vacuum

[Leedsharlequin]

Did the pipes , airbox mod and jetting and running sweet. When I run her pretty hard and come to a stop there is a noise in the engine area that sounds like a vacuum/slight humming, just for a few seconds. Any thoughts

 

[Texas94fs]

you gotta love the sound of air being sucked in when you whack open the throttle! could just be the throttle plates not closing all the way down for a second or so so the bike is still sucking in extra air

 

[grumpy_1944]

Happy happy

Did the pipes , airbox mod and jetting and running sweet. When I run her pretty hard and come to a stop there is a noise in the engine area that sounds like a vacuum/slight humming, just for a few seconds. Any thoughts

The "humming" sound is just a happy Bonnie 'cause it just got rode hard.:ride: Just don't put it away wet!! :nono:

:lol3::lol2:

 

[Delbert]

One possible is you sprang an exhaust leak that you'll only hear at idle, get your ear(or a piece of garden hose) down to the muffler clamps and listen for the hissing sound and get it fixed, and the other is now that you did the air box mod, you now have extra air going in to the carbs and it's just noisier and more pronounced over the stock air box-- which is nothing to worry about.
Del