Choke activation on 1982 CB750c

[DoubleMal]

Hello all,

just pulled off the carbs from my '82 C to *finally* see about cleaning them out and improving the starting of my bike.  Now that they're on the bench I note that when I lift the choke activation lever the butterflies don't move (ie. I pull the armature and the spindles with the four butterflies just sit there).  The butterflies do close if you push them with a finger (while holding the choke activation lever up) so they're not seized - this seems weird to me.  Am I correct in assuming that when I pull up the choke lever (the one actuated by the choke-cable when everything's installed) that the four butterflies should close?  Given the number of PO screwups I've found on the bike I'm assuming that the cams connecting the butterfly spindles and the activation lever are either broken or improperly connected.  Any thoughts?

Pete

[TOOLS1]

I think you are totally correct.
TOOLS

[Re-run]

I don't know the cb carbs you have but my v45 carbs are cv as well and the choke doesn't turn the flaps, it opens up a fuel line to dump in more fuel. The throttle controls the flaps. Pull the throttle cable and see what moves.

[icerigger]

Possibly the spring has become disengaged from the choke shaft.

Download the Macgregor cleaning manual and somewhere around page 30 it tells you how to set this up.

[DoubleMal]

Thanks for the validation and the ideas, everyone!  I'll check the spring carefully - I did try rotating the throttle as well but the choke butterflies are not attached or linked directly...

[shinyribs]

Icerigger is on the right track. They are actually spring loaded in to the closed position. Pushing the choke cable to the 'off ' position overcomes the springs to open the blades.

I had some trouble with a cold start lately and found only half of my choke plates were closing. My problem was a bent shaft in the 3-4 pair of carbs. The friction was greater than the strength of the springs and would allow them to close.

Good luck and let us know what you find.

[DoubleMal]

Thanks Icerigger and Shinyribs for the advice...  It appears that the spring is attached (and correctly too) but, similar to Shinyribs' post, the spindle on the #1/2 carb is really stiff (not sure if bent or simply gummed up).  The pressure applied by the spring when the choke armature is lifted is just doesn't provide enough force to overcome the binding so none of the choke plates close.  I'll complete pulling the carbs apart tonight and hopefully it's just gunk and not a bent spindle...  Thanks again, all!

[DoubleMal]

Thanks for the advice everyone.  I got the carbs rebuilt and back together and the choke is now working correctly.  In the end the issue was a combination of some corrosion on the spindle connecting the #1 and #2 choke butterflies plus the fact that the PO had not properly aligned all four carbs on the interconnection rails.  Once the corrosion was all cleaned away and the four carbs were carefully aligned the choke butterflies move correctly...