Air door question

Not sure what you call it, the 'air door' on top of the airbox. I'm wondering, is the operation dependent on engine load (ie full throttle) or opens at a certain rpm?

Reason I ask, if I give it full throttle in 3rd gear at 4500, it doesn't accelerate much, but then a few seconds later the sound in the airbox changes and it snaps my head back...some.

 

The flapper valve on top of the Air Box is operated on a vacuum line from the engine. If disconnect the line and plug the hose the valve will remain open. If you like it leave it, if not just reconnect it. You can also type “flapper valve” in the search engine and read more post on the subject.

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Or, you can remove it entirely, along with the actuator and snorkel:

 

What exactly is it's purpose?

 

I've heard that it's to help quite the bike down at lower RPM's. I disconnected mine and could not tell any difference in performance. I usually ride with ear plugs and didn't notice much of a difference in noise either. Like I said it's an easy thing to disconnect or reconnect so give it a try and see if you get the result your looking for.

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To help pass the EPA mandated drive-by sound test.


Every DBa helps.