Topic: 350F carb float problem. Stumped.

[Exbex1]

Good morning.
Rebuilt my carbs following a very good online article by the vintagebikebuilder. Great resource. Floats set at 21mm on the bench before install. Ran the bike yesterday for the first time since reassembly following broken cam chain tensioner bolt. Very very rich. Crazy rich. Barely ran.
I removed #1 float bowl and found the problem. With the bowls empty, the floats drop too much and the needle comes way out enough so there is a “hitch” with it going back in. Because of that, the float doesn't float, its stuck all the way down and the needle is so open its almost falling out.
I just need the floats to stay a whisker higher when bowls are empty to prevent this.
Is that the job of the upside down “v” bracket that hangs on needle seat? They don’t seem to be doing their job. I removed #4 bowl and found exactly the same issue. I'm fairly confident I put them back together correctly, but something is obviously wrong.
Any suggestions? I hate to start bending stuff without some more knowledge.
Happy Memorial Day and thank you all.

[denward17]

Float upside down?

Pictures would help.

[Exbex1]

Good morning. Thanks for reply. I thought that too but they only fit one way. I’m going to try to get some pictures very soon.

[Vfrman]

Good morning.
Rebuilt my carbs following a very good online article by the vintagebikebuilder. Great resource. Floats set at 21mm on the bench before install. Ran the bike yesterday for the first time since reassembly following broken cam chain tensioner bolt. Very very rich. Crazy rich. Barely ran.
I removed #1 float bowl and found the problem. With the bowls empty, the floats drop too much and the needle comes way out enough so there is a “hitch” with it going back in. Because of that, the float doesn't float, its stuck all the way down and the needle is so open its almost falling out.
I just need the floats to stay a whisker higher when bowls are empty to prevent this.
Is that the job of the upside down “v” bracket that hangs on needle seat? They don’t seem to be doing their job. I removed #4 bowl and found exactly the same issue. I'm fairly confident I put them back together correctly, but something is obviously wrong.
Any suggestions? I hate to start bending stuff without some more knowledge.
Happy Memorial Day and thank you all.

Im about to start my car rebuild on my 350 F. Could you please provide a link to that article by vintagebiker?  Good luck on your float issue, I sure hope I don’t have to deal with that

[Vfrman]

Never mind, I found the article: https://www.vintagebikebuilder.com/cb350-400f-carb-rebuild-demonstration.html

[Exbex1]

Here's the carb article. It's very very good. I am not a pro and it was easy to follow. Very thorough.

https://www.vintagebikebuilder.com/cb350-400f-carb-rebuild-demonstration.html

Also, here’s a picture of what I'm talking about. See how far down float is? See how the needle is over extended and crooked? It’s just enough to stick the float down.

Lesson learned. If I had bench tested for leaks, I would have known something was wrong.

Hopefully this is an assembly error but I cant't solve it.

Thanks.

[Nurse Julie]

Something very, very wrong there 🤔🤔🤔🤔
See the difference?

[Exbex1]

I do. Mine hang way too far down when bowl empty.
I don’t get it. I didn’t bend anything other then the tab ever so slightly to set full height.
I gotta do some more digging. I can’t see how they are wrong, but obviously they are.
Thanks for your pics.

Tom

[Nurse Julie]

I do. Mine hang way too far down when bowl empty.
I don’t get it. I didn’t bend anything other then the tab ever so slightly to set full height.
I gotta do some more digging. I can’t see how they are wrong, but obviously they are.
Thanks for your pics.

Tom

Are you setting the floats with the carbs standing upright in the horizontal position? because that's how you make sure you get the measurement correct. Are you also measuring from the top of the float to the face of the carb bodies and is the tang only just touching, not depressing the float needle at that measurement?
Also, the floats will hang right down into the float bowl if there is no fuel in the bowls as gravity makes them drop. It's the fuel in the bowels that lift the floats to shut the needle valve off. Look at the floats again.

[MauiK3]

Are they the correct floats?

[bryanj]

That float is upside down!

[Nurse Julie]

That float is upside down!

I didn't want to state the obvious Bryan, that's why I thought my photos would be of use 😊😊😊

[Bodi]

The first time I took all the floats out this was an issue. They definitely look "right" when upside down.

[Exbex1]

Humble pie eaten.
Thank you gentlemen.
Obviously not an expert but trying.
I think maybe prior owner had em apart and i copied his mistake?
I should have caught it.

Happy Memorial day.

Tom

[denward17]

Humble pie eaten.
Thank you gentlemen.
Obviously not an expert but trying.
I think maybe prior owner had em apart and i copied his mistake?
I should have caught it.

Happy Memorial day.

Tom

I've eaten a few humble pies myself, that's how we learn. 

[Nurse Julie]

Humble pie eaten.
Thank you gentlemen.
Obviously not an expert but trying.
I think maybe prior owner had em apart and i copied his mistake?
I should have caught it.

Happy Memorial day.

Tom

Thats enough of the Gentlemen, I'm female 😂😂😂😂 No offence taken.
It's a learning curve and we've all been through similar things with these old bike and it's how we learn.

[Exbex1]

Thank you all.
I'm sorry about the gentleman thing!
I don’t have much of an ego. As long as I learned, and my old bike will run, I'm good!
That’s why I came here (again)!
At least it just ran rich and didn’t explode and seize up. I had it in 1,000,000 pieces on my bench this winter!

Tom

[Exbex1]

Hello again.

Im afraid more clarification is needed on which way my floats go.
Here’s a picture out of the Clymer manual, and a picture from the Partzilla diagrams and a picture from a great paper written by “Thevintagebikebuilder”
If you look, they all show the round part of the float facing into the carb, not the bowl.
That’s how I installed mine when I redid my carbs.

I yanked my carbs off this AM, and flipped over the floats so now the round part is pointing into the bowl. I went back and looked at pics and am now confused again. It doesn’t seem right.


Thank you for any help.

Tom

[Oddjob]

It's upside down, ignore the parts book. Look at your pic of the float fitted, now imagine it the other way, the brass bracket would be much higher up than your pic shows, this would then mean the float valve would not be hanging out of the float valve seat. Look of the pics Julie posted, they are fitted flat side up not down as yours were.

[Don R]

 It's too bad that once an incorrect photo, drawing or description is out there, people continue to copy it and then it continues to create havoc. 
  Often the people writing the manuals haven't ever done it themselves.

[Little_Phil]

Are you sure? Looks right All the 350s and 400s are shown flat side down. It just looks in pic on reply 5 that the tang is not bent anywhere near enough up.
pic of carbs on sold on ebay:

[Oddjob]

I'm a little concerned here that Julies pic may be of the wrong carbs, possibly 500 carbs, look at the float, it has a tang on the brass bracket that stops the float from descending too low by hitting the pillar, thus stopping the float valve to hang out of the seat, the 350/400 doesn't have those tangs, the 500/550 does.

Also look at this float on UK Ebay, 3rd pic shows clearly the mark left by the pin on the float valve, https://www.ebay.co.uk/itm/386826909656?itmmeta=01HYTWZSEKRTQBCJG94VEF5FA2&hash=item5a10ae37d8:g:rmUAAOSwd0BVxSrE&itmprp=enc%3AAQAJAAAAwM6AdnHV6y0GURYlXCyPgFvSaL%2B52d4eYNLbFC%2BeUuL6d6SRoaMyWP2nOcQArG8Gx9dJZYm88gbPr6TiXxHtSCp8k81UA7iZ1o3IARkWKqBm4vSQlsEb4OC%2F5jZ4fqSiK4BrLY7Iw1xOu1usOr4sQBd604LN48yb1lt5XBI2S3BEWf%2B7lK3wbETEluxPOwvKp%2BgXSLPWdfFmiiD%2F2dFOZ9LdzLNVzieaLoC4F%2FQ0eB2FYKTf3%2FRRGL9dmNqxnQCD2Q%3D%3D%7Ctkp%3ABk9SR8iX_9z2Yw and that shows the float sits with the flat side facing up into the float bowl. Maybe Exbec can inspect his float too see if that has any witness marks.

[carnivorous chicken]

Folks, flat side down is correct for 350F carbs. There is even an small chunk out of the top (round) part of the float that corresponds to a small protrusion in the top of the carb body. I was questioning my sanity but I took a bowl off a spare set and tried to put the float the other way around, it doesn't work.

The tricky thing with 350F carbs is that if the bowl is dry (including from parking/sitting for a few days and the gas in it evaporates) the floats can definitely hang low enough to bring the float valve out enough so that it catches and doesn't operate properly, leading to the bowl overflowing. Usually a rap with a mallet will work. This can happen, of course, after a rebuild after putting together dry carbs.

[Exbex1]

Thank you. They still don't work, but I did put them together correctly!


Sub question for carnivorous chicken,

Can i bend the upside down “v” a little? Is it just a bracket? I really only need to hold them up 3/16th's of an inch more and they would not drop enough to be a problem.

As always, thank you for the discussion.

[carnivorous chicken]

Thank you. They still don't work, but I did put them together correctly!


Sub question for carnivorous chicken,

Can i bend the upside down “v” a little? Is it just a bracket? I really only need to hold them up 3/16th's of an inch more and they would not drop enough to be a problem.

As always, thank you for the discussion.

I wouldn't -- those things can be brittle.