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I have been looking at a hypercharger for my vn900 custom, but i was wondering how the butterflies work? Every video i see shows that when the bike is off the butterlflies are open, shouldn't they be closed when the bike is off and then open when the bike is on?
 

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I have been looking at a hypercharger for my vn900 custom, but i was wondering how the butterflies work? Every video i see shows that when the bike is off the butterlflies are open, shouldn't they be closed when the bike is off and then open when the bike is on?
The butterflies will be closed when the engine is generating a high vacuum as in idle and cruising. When you go to a more aggressive throttle then the vacuum will drop and the butterflies will open fully.
 

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The butterflies are never fully closed. They slightly flutter at idle but like Sojourner said with more throttle they will open more.They are vacuumed operated(tied into your existing vacuum line) but are fully opened when the bike is not running.If you do get one,let me know and I will email ya the colorful and very easy to follow step by step instructions how to install it. They were posted on this forum quite awhile ago and not sure if they are still floating around,but when I got mine I saved and printed the posted thread.I have a classic,but don't think there is any difference in the install(in fact I think the instructions were for a custom....BV is clouding my memory right now)
 
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