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New (to me!) '77 CB400F - US model
mattsz:
The choke lever turns the choke plate shaft on carb 1. There's an adjustable linkage between the shafts of carbs 1 & 2. Another adjustable linkage between the shafts of carbs 2 & 3, and another between 3 & 4. See photo:
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Each of the linkages on my rack were adjusted with a little gap between the set screw and stop. So, choke 1 plate had to rotate a bit before choke 2 plate began to do the same. Choke 2 plate had to rotate a bit before choke 3 plate began to move. And so on - by the time choke 1 plate was fully open, choke 4 plate had a ways to go - as seen in the photo a couple of posts back.
I don't know if mine are normal, or if there's something wrong with the mechanism, but I can't adjust them so they all open together as a unit and close together as a unit, ending up in the same positions at each extreme of travel. Hence my question about which choice is the better one.
Having changed the adjustment for equal open position, you can see the above photo also kind of shows how, when the choke is closed, even though the #1 choke plate is fully closed, each successive choke plate remains open a bit more than its neighbor to the left.
Here's a pic of the readjusted plates in the open position - all the same (compare to the photo a couple posts back)...
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Bryanj:
I am probably wrong but i thought there was a spring in each adjuster
mattsz:
--- Quote from: Bryanj on April 13, 2020, 08:53:40 PM ---I am probably wrong but i thought there was a spring in each adjuster
--- End quote ---
Each choke plate shaft has a spring forcing it closed. Tightening each adjustment screw pushes the plate "open." I think... I just did it a couple of hours ago, and I've already forgotten... :-[
mattsz:
Some observations...
All four float bowl o-rings were glued securely in place with plenty of some sort of goop. Will have to clean them all off...
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#4 float bowl has a mismatched screw - bigger head, and shorter thread which is somewhat stripped at the end (although the pic doesn't really show it). The proper screws seem to work in all four positions (carb body thread isn't damaged), so I'll get a correct replacement...
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mattsz:
While we're playing with 400 carbs, I have another choke operation question.
There's a cam-driven linkage which appears to tie the choke to the throttle. As mine is currently adjusted, when the choke is open (normal operation), there is a gap between the choke lever linkage and the adjustable set screw on the throttle mechanism:
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When the choke is closed, the cam shifts the linkage slightly - in theory, I suppose, to push on the adjustment screw and open the throttle a bit:
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Mine is currently adjusted so when the choke is closed, the linkage just touches the adjustment screw - but it doesn't actually open the throttle at all. Is it supposed to open the throttle? My copy of the service manual doesn't mention it...
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