Topic: '78 cb750 f CARBS - choke question

[dboblet]

Bike: '78 CB750
Carbs, Kei-Hin PD42A
I've got the things off (god help me when I try to wrestle them back on again... and keep the kids away or at least play loud music to drown out the expletives)
And I've noticed that when I pull up on the choke lever, the two left carbs (3 $ 4) 'sort of' close, but the 1 & 2 carbs just remain open.  Some close scrutiny shows that maybe the spring for the 1 & 2 carbs is either broken, or not hooked up right.  I'm not sure how this is supposed to go and the diagrams in the service manual are only somewhat helpfull... so if someone could talk me through how it's supposed to work, before I uncouple the carbs (grrrr) I'd be thankfull.
I note that there is a very strong return spring that works perfectly for all butterfly valves when I want to have them open again.  The shaft for the 1 & 2 carbs might be a bit 'stiff' so perhaps I should take 'em apart and pull & clean the shaft anyway. 
What say you?

[jjwaller]

First of all, cylinders are 1-4 left to right.
The choke bell crank is attached to the 1 and 2 carbs.
And then spring coupled to the 3, 4 carbs.
Next to carb 2 should be coil spring to open choke butterflies,
then bracket and then smaller coil spring that couples the left
shaft to the right shaft.
Trying to post some pictures of my spare carbs,
but I'll have to work on that.

[dboblet]

OK, I bit the bullet and pulled the carbs... again.  THIS time I was meticulous and took every thing apart I could find to take apart.  Blew out all the orifices with a commercial propellent cleaner in a can.  I found the idle jet needles had some ... deposits on them.  So, I cleaned them off with some gently applied 600 grit sandpaper.  Then I reset the float height per spec... well almost to spec.  I allowed for the current 'less dense' fuel mixtures we use at the pumps 30 years after the bike's specs were written. 

I hate to say it, but I also checked the point timing (static) and was flabbergasted to discovered that though the points were gaped correctly, the 1/4 points didn't open until TDC....  The 2/3 were right on the money... Wear???  I put on new points and all was good with the world.

When I finally got enough fuel in the bowls for the bike to run... perfection.... almost.
I didn't put the air box on so I know it must be running a bit lean, and had the associated symptoms.  Progress, baby steps....