Choke linkage malfunctioning?

[lusciouslemur]

Hello everyone, newbie here. I just finished a carb rebuild for a 1980 750c, so far so good, but the choke mechanism seems to be flawed. The hook for the actual choke cable doesn't open or close the valves, meanwhile the shaft for carbs 3 and 4 does. I will post a video shortly. Any thoughts on why?

[lusciouslemur]

https://www.youtube.com/watch?v=zMVgk6i2CsU

There is a video describing what is going on. I have more pics I can post as well. I've been following the manual and the Sean G carb rebuild guide, but no luck yet.

[Re-run]

I dont have an 80, by my vf700c has cv carbs. The flaps open from vacuum on mine. The choke merely dumps in more fuel.

However, your video makes it look like the linkage is not set right. The linkage on the 78 carbs are similar and if they are not mated right, only 1 side works.

[TOOLS1]

I have to second re-run. It sounds like the choke rods are not properly lined up in the middle where they meet.
TOOLS

[Maz]

From what I remember when I stripped and rebuilt mine, the choke flaps rely on the spring, joining the 2 pairs together, to open and close. If the carbs are bolted back together slightly wrong, the shafts bind a little and the spring pressure can't overcome the friction, however, with a bit of manual assistance like in your video, they open. It may be worth slackening the bolts that hold the carbs to the retaining plates, just to see if they move back into line. Also, I seem to remember that the spring in the middle has to be wound under tension for one turn, before hooking it onto the mechanism. Very fiddly but can be done using a hook made from stiff wire, like MIG welding wire.

Maz

[lusciouslemur]

When I purchased the bike, the same problem existed before I broke down the carbs. Oh well I thought, i'll get to that when I rebuild it. Even with the retaining plates off, same problem. The spring in the middle I have wound as tightly as it can go, I tried to get one more turn out of it but it didn't give. I'll try again though because that might be what I need to do, turn that spring around one more time.

[lusciouslemur]

Maz, I think you're right, I unwound and reset the spring linking them together and now they close about halfway. Just for fun I wound the tooth holding the spring for carbs 3-4 with carbs 1-2 using a paper clip and that made them close and open 100%.

[Maz]

Hopefully that's fixed then!
Funnily enough, I have just been to my garage and I was playing around with a spare set that I have and I thought "It's got to be that spring"! I was just about to post another reply to you when I saw your post!

Maz

[heath1066]

My choke valves were very sticky after rebuild, I found oiling the mechanisms properly (spring and such) fixed everything beautifully.

[heath1066]

Just watched the vid, that's exactly what happened with mine, proper lube fixed it