Author Topic: 400f 1976 carburetor separation/disassemble don'ts  (Read 475 times)

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Offline Redline it

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400f 1976 carburetor separation/disassemble don'ts
« on: December 13, 2019, 03:49:31 PM »
recently separating carb racks the large brass cap was fairly too tight for my judgement so i left it on and only slid off the shaft lever, after removing the dust cap "B," then removed the 8 stay screws, and simply spread the carbs just enough to get to the fuel "T" out, that freed the right pair of carbs from the stay, and leaving all link arms connected was able get to the fuel connector out of that, and left 2 carbs stayed connect to the stay by the throttle shaft link arm, still they can be pulled away from the stay to separate those as well.

the manual describes a total disassembly part by part that only includes the separation as if you're going to completely disassemble, it is not required nor advised IF the brass caps (usually the outsides,) are pretty tight or slightly cocked (from cross-threaded) assembly by the PO.

the reason to not attempt it, is if you don't have spare parts, if it's tight, and you try to break it loose, here's what can happen, if corrosion has built up inside from the 2 dissimilar metals aluminum and brass or if it's been lock tite'd from PO then taking it off can wipe the tiny threads off enough that makes it almost impossible to reassemble or at best there'll be a couple thread left to hold the cap on.

i decided to follow the instructions with a spare carb rack to get operational and of course that's what happened, even care of lubrication and easing it out back and forth. so much more complicated than leaving it all together.

(on account the running carb/bowl joints are bowed too much to get a seal." So the fix i'm trying to crimp the cap some with a flaring tool, like a resizing die the wing nutted style. it's not working so well. i don't want to have buy some form a thread kit to fix it. at last resort i'll put some copper thin shielding as a fill in or aluminum foil. what the cap screws onto is compressed slightly as well, making the spring inside too tight to move freely, but that looks to be a train wreck by trying to expand that delicate thing without cracking it. could of left this short and said just don't take them apart, but if you're like me and  forever an apprentice with not much good luck, then you wouldn't understand why not. they are super delicate. and still i cannot figure out how to take those weird spring things off of the ball joints, and i don't want to know. and certainly do not attempt to remove the pin holding the throttle shaft through the stay plate. (luckily i wouldn't try.) 

Offline Alaxy Galaxy

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Re: 400f 1976 carburetor separation/disassemble don'ts
« Reply #1 on: December 14, 2019, 03:38:10 PM »
You could just replace the links.

There are one of each side on eBay right now. They're not terribly expensive either.

https://www.ebay.com/itm/113721000720
https://www.ebay.com/itm/113721000741

Offline Alaxy Galaxy

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Re: 400f 1976 carburetor separation/disassemble don'ts
« Reply #2 on: December 14, 2019, 03:45:08 PM »
Or get a whole set without the brass caps and various springs and balls for not much more than the cost of one link with.

https://www.ebay.com/itm/382282704021

In any event, CB400F and CB350F carbs are identical, save for the number stamped on the body and some of the jets, so you can double your search results by looking for them as well.

Good luck.

Offline Redline it

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Re: 400f 1976 carburetor separation/disassemble don'ts
« Reply #3 on: December 15, 2019, 03:51:37 PM »
Or get a whole set without the brass caps and various springs and balls for not much more than the cost of one link with.

https://www.ebay.com/itm/382282704021

In any event, CB400F and CB350F carbs are identical, save for the number stamped on the body and some of the jets, so you can double your search results by looking for them as well.

Good luck.

thank you, the only problem with changing the links 1 or both sides is that cloth like rubber thing, maybe a dust cover for the balls have to come off to put another one on. and although i found out they are supposed to press off and on the balls i tried last night wasn't looking like an easy slip without breaking it, even with heat. plus the one set of carbs i was gonna change the link from, all brass caps are on so tight that they're gonna twist the socketed links.

the one that's needing replacing, apparently was mated or married to the brass cap, by extremely overtightening, and the top of the aluminum link about the thickness of underside "b" dust cover washer was powdered. my fix is gonna include a ring shaped dust seal to go in the cap, shorten the spring about that washer thickness and drill small hole for a cotter pin through the cap (only that might eventually pull  through the link top,) or the other style of clip like the rear axle type, it'll have more spread out load from the spring pressure. i might check out that ebay link. thanks again.

Offline Redline it

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Re: 400f 1976 carburetor separation/disassemble don'ts
« Reply #4 on: December 16, 2019, 10:23:48 AM »
thanks for the help. i epoxied a film on a piece of aluminum foil folded three time and glued it to the threadless cap sync arm, wrapped it around tight 1 wrap with 1/4 in overlap, didn't wait for the hardner to finish, soon as i could get the thing on worked like a champ. i tightened it finger torqued pretty high on the scale, left it. if it falls off i'll put a grease zerk in it. i rode this bike since the early 80s and only bought gas oil and a set a tires, nothing else. 2014 started buying ebay upgrades, that stuff last about  year if im lucky.