secondary throttle engagement

[foxy]

Secondary throttle butterfly has not been engaging for length of ownership (I'm assuming). Have taken the carburettor off the manifold and can clearly see that upon the primary throttle rotating, the secondary linkage does not drop down, is the diaphragm? that is connected to the linkage to blame? I can rotate the secondary linkage by hand easily enough. Anybody have an opinion? I think the diaphragm thing makes a clicking noise when the secondary linkage is rotated by hand.

[beaver]

Its vacum operated so pull the vac unit of the side and check the diaphram for damage. Also you can blow/suck though the holes in the side (when its off) to see it it works and holds vac. And check the holes into the carb are clear

[Bartman]

The daiphram pulls the butterfly open when the engine is running using vacuum.