a vacuum can?

carnut14

New Member
Sep 10, 2019
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So yesterday I purchased my first bike. Its sort of a project put it was/is? a runner. The fellow I purchased it from had multiple bikes for sale and all (natch except the one I chose) had a small juice sized can that was attached to the carb manifold via a small vinyl tube. The can typically had a screw on lid that sealed with an o-ring. Any one know what this thing is and/or why it would be required?

New to the forums, apologies if this is posed in the wrong place.
Carnut14
 

FOG

Well-Known Member
Mar 3, 2019
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Sounds like a boost bottle and not required. The idea is to set up some kinda resonance in the intake tract to widen the powerband on a 2 stroke motor. The volume of the "bottle" is normally somewhere near the displacement of the motor itself.

There are people whose opinions I respect that claim they are useful on smaller 2 strokes ... and I may try one myself someday.:)

I hope that's the correct answer to your question. Best guess anyway.
 

Greg58

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May 1, 2011
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I’m with Allen, the only way to prove the boost bottle is to try it myself. I have one bike that I’ve been using to test several pipes on that I will try it on, I’m not buying a kit I’ll make it myself.