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Discussion Starter #1
Hi All;

I'm new here (well, new to posting here) and I'm trying to rebuild the VB22A carbs on this bike ... I've gotten them mostly apart (but not yet separated) and I'm confused about the throttle .... where the cables attach, I am completely unable to turn the shaft that the cables and butterflies are attached to. It will move a very small amount towards "closed" but when I try to move it to open the butterflies, it hits a stop and is completely frozen. Not just tight or gummy ... it hits a hard STOP. Butterflies don't even attempt to move. I've cleaned with carb cleaner, applied liquid wrench, soaked in Pine-Sol, blew dry, and now soaking in some Marvel. I'm afraid to force it. Am I missing something, or do I just need to keep cleaning / working it? I've searched the forum and haven't seen this issue posted. Working on these carbs (or any carbs) is brand new to me. But I swear it feels as if it's mechanically locked!! I will post a few pics, can post more from different angles if it would help. I have no idea what's holding it shut so I don't know exactly what to focus on, cleaning-wise, mechanically, or pic-wise. I appreciate any help!

Josh
80 CM400T
 

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Pictures from every angle you can think of will help. I haven't seen frozen throttle shafts on these but it's possible. Go ahead and separate the carbs.
 

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Discussion Starter #3
Here's a couple ... I have more, just waiting for them to get to my cloud from my phone. You can't see it here, but in this position the throttle butterflies are shut. Which way is the throttle supposed to turn? Judging from the way the closed butterflies are currently angled in the throats, it seems that it should turn towards the choke butterflies (airbox) but again, completely new to me so I really have no idea...

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Using the 2nd picture as reference the bell crank for the cables rotates clockwise
 

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OK, get the carb insulators off the carbs and split the carbs. See if either carb will work separated, I suspect the left one is causing the problem.
If it's the left then remove all of the choke linkage/springs/etc. and see if it moves. NO, the remove the longer rod with the spring and try again.
 

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Discussion Starter #7
OK, get the carb insulators off the carbs and split the carbs. See if either carb will work separated, I suspect the left one is causing the problem.
If it's the left then remove all of the choke linkage/springs/etc. and see if it moves. NO, the remove the longer rod with the spring and try again.
[/QUOTE
Will do, thanks Jim! I'll post with updates.
 

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Discussion Starter #8
By the way, I have read through your awesome VB carb rebuild post, fantastic information. Between that, the FSM, and the Clymers manual, I'm feeling (perhaps naively) pretty ok with tackling this job. Thanks again!
 

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Discussion Starter #11
Well, finally got the left carb throttle shaft to rotate, after a lot of firm but polite persuasion. It's still awfully stiff it seems... It's returning to "idle" from "full throttle" on its own now as well ... But it takes a full 13 seconds (hey, that's down from 29 I started with!). How easily / quickly should these guys return to shut from wide open? I was expecting instant, or close to it.
 

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They should snap shut. I would continue to flood the shaft area with something like Kroil or even WD40 and keep working the shaft. There's obviously debris or corrosion that causing the bind. \
Or remove the throttle plate and pull the shaft to polish the bore and shaft with oil and 2000 grit or higher sandpaper. This is the best course to follow.
 

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Discussion Starter #13
Awesome! So to pull the shaft from the carb body, it's as simple as removing the butterfly plate, then pulling the shaft out the side? It might sound obvious but it's so sticky that I don't want to be applying a lot of force if there's more to "undo" to get that shaft out.
 

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Just remove the screws and wiggle the throttle plate out. Do not do anything that will damage the edges of the plates, the temptation is to try driving it out by tapping on the edge. Those are critical surfaces for the carb to work. You can use pliers to pull IF needed but try to do it by hand.
Scratch identifying marks on the plate for up and which side faces what(back/front), one mark will do both. These are JIS screws so if your screwdriver has a point file it off so it fits the screw completely.
 

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Discussion Starter #15
I got the shaft out of the right carb. Once I got it, cleaned it good. However, in the brass insert (pictured) was what may have once been a gasket? It was under the washers in the pic. It was crazy sticky. I really can't tell if it's sticky debris, or some sort of paper / cardboard gasket, or what. I test fitted everything back together, sans this "gasket", and it turned beautifully, with zero play. Should there be some sort of gasket here, or is this just 40 years of gunk? It's been pretty obvious through this build that these carbs have never once been opened.

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That was a felt washer, emphasis on was. Hit a fabric store for a small scrap of felt and make a new one, then pack it with grease and insert.
 

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Discussion Starter #17
Awesome, thanks Jim, you've been a lifesaver!! I didn't make orientation marks on this one so I will on the next, that's a great idea. I test fit it both ways and found the orientation with the tightest seal. No gaps whatsoever! And in order to wiggle the plate out the first time, I covered it with a shop rag and used needle nose pliers with juuuust enough pressure to hold, wiggle, and out it came.
 

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Before you lock down the screws operate the throttle several times pulling and pushing on the end of the shaft to be sure it is centered side to side. Once everything is set tighten both screws, then remove one and put a small spot of Red Locktite on it, tighten and repeat on the 2nd. Worst thing in the world is for the engine to swallow one of them after they loosen up.
 

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Discussion Starter #19
Good call on the butterfly screws. I see now why they are peened from the factory. Also, while I did completely remove the butterfly AND shaft from the right carb, I was able to simply remove the butterfly from the left one (and marked it this time!), that gave me enough room to pull the shaft a couple mm or so "out" without going completely out (I really didn't want to remove all the springs, etc) and really shoot some cleaner into where the shaft goes through the body. Between working it back and forth sideways, and simultaneously twisting it, cleaning, blowing with compressed air, it freed up good. Got the butterfly back in and set, and that thing springs like a dang mouse trap now!!! Thanks sooo much for helping me through this. It's been a success! On a side note, while I was at it and studying how the choke interacted with the throttle, I went ahead and lightly polished that tang on the choke shaft that interacts with the arm that slightly opens the throttle at full choke. Looks like there are two "bumps" in the tang actually that give a little throttle at partial choke and a little more at full. In any event it definitely helped the choke mechanism operate more smoothly.
 

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Good deal. Polishing interacting pieces can never hurt. Yes, the choke is setup to raise the idle speed slightly depending on choke position. Be sure to lube the choke linkage bolt and bushing area.
 
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