anti-reversion chambers

[doc_rot]

I've read a bit about them, I'm thinking about fabricating some to try in my custom headers. Does anybody have any experience with them? The theory seems to make sense for an engine with the same valve port diameter as the header. here is what i'm considering for my KZ750 twin.

 

[irk miller]

IIRC, most people that use them do so when they're running cams with a lot of valve overlap. They're also typically run further downstream.

Look up Jim Feuling. He's was a major inventor and innovator for AR tech.

 

[doc_rot]

Thanks for the Jim Feuling tip, some interesting reading there. It makes sense that a lot of cam overlap would necessitate these. I have seen them run at the head and just after the first primary bend. In those situations (after the first bend) it seems that they are dealing with space issues and need the header to start bending immediately after the head. By having the AR chamber at the head the header would stick out farther overall and not fit wherever they are cramming it.
I have found that there is some consensus that even with an anti-reversion insert it is good to have the primary be bigger than the exhaust port. What about going bigger for the first bend and then tapering back down to a smaller size to maintain velocity? (EDIT) after reading a bit further I have determined this is a bad idea. if anything the desire would be to step up after the first bend.