Tillotson experts?

[old2stroke]

Some HS models have a device that is referred to on the parts list as a "hi speed govenor valve".  Does anyone know the purpose/function of this thing?  It is a check valve with a fixed orfice and it is located in a passage between the fuel chamber and the main venturi but the valve seems to be in the wrong way to supply fuel.   

[Cut4fun]

I dont know much on this. But here is what I noticed. It is a brass fitting that somehow rev limits your carb settings. Keeps a idiot from leaning their saw out so far and burning it up, the gov thing lets fuel by  and sort of makes the saw really rich like a 4 stroking sound. Say saw carb is 12k rev limit and you adjust carb to lean it will sort of flood it with extra mix. 
I have learned to bypass the system, I just place a BB inside and screw the brass fitting back in.
Hope I made some since.

[rayrayrau]

A low tech rev limiter.  It works off the vibration of the saw and will pour in extra fuel when the rpm/engine vibration go past a point.  Also known as a "buzzball".  When the saw is under enough load it will stay closed, but under light or no load it will open to keep rev's down.