Struggling with 750 Keihin Rebuild

Did a full tear down and clean up on the carbs from my 750/4 and now putting them back together. Each body was fully torn down and soaked in carb dip. Everything going nicely until trying to get the choke linkage to operate smoothly. The return spring is very weak, and the butterfly's hang up. Have checked the spring every which way and I'm positive it's installed correctly. Going to take the carbs back apart and look for debris in the choke rod bores, but if anyone has any words of advise please share.

Yeah...I have the same problem. Two butterflys move nice, the other two supposed to move by the spring force doesn't.
Spring is very weak, may be you can put a stronger one?

Btw, I can live with that. You only have to (when you apply choke) push the metal that is part of the second shaft of butterflys...

If you small hands that is no problem.

I had similar problem a few years ago. I had difficulty starting the bike and found that the choke butterflies were only operating on 2 carbs . I can't remember exactly what I did. I think I took the carbs off, cleaned all the linkages with Q tips and used light machine/lubricating oil.
I have never totally separated the carbs from each other for cleaning.

Thanks for the responses guys. The choke return design seems weak in my opinion. The spring coils around a post/boss cast into the carb body. Can't increase the spring preload by winding the spring tighter because as you do so the diameter reduces and the post is too fat. Thinking about shaving down the post so the spring can be wound tighter. Going to verify cleanliness of the carb bores and maybe run a little sandpaper though there to make sure there isn't any hidden corrosion. Also lightly polish the shafts. If that doesn't work, will go after that post...