Post by: Nurse Julie on April 08, 2019, 05:08:21 PM
Question.....on carb floats, should there be a dip in the tang or should the tang be straight?
I still have a pissy carb on the 550 so just going through all the usual diagnostics and was just wondering if the actual shape of the tang makes any difference to the float height?. I can't see how it would but thought I'd ask (him indoors is busy).
Photos of one of my tangs. CB550/4 F carbs.
Ta
[attachimg=1][attachimg=2][attachimg=3]
Post by: K2-K6 on April 08, 2019, 05:27:47 PM
But think it was kevski that uses something like cutting compound on the valve seat to make sure it's properly clean and free of abrasion defects to work reliably.
Could use small dowel rod in a drill with t-cut to gently spin it on the seat to give it a polish.
Post by: Nurse Julie on April 08, 2019, 05:50:20 PM
I don't know if what you have is factory or not, so no advice on that.Thanks Nigel. I have tried cleaning / polishing the valve seat, made no difference. No splits in overflow brass pipe in the bowl. Float moves lovely on the little bar, float has no holes in it as I tried drowning it in a bowl of petrol, no go, keeps popping back up and float set at 22mm. I would be interested to know what the tangs were like from new though.
But think it was kevski that uses something like cutting compound on the valve seat to make sure it's properly clean and free of abrasion defects to work reliably.
Could use small dowel rod in a drill with t-cut to gently spin it on the seat to give it a polish.
Post by: kevski on April 08, 2019, 05:52:31 PM
Post by: Nurse Julie on April 08, 2019, 05:54:35 PM
I have never seen tangs with curves, only straight,Mmmm, interesting
Post by: Johnwebley on April 08, 2019, 05:54:36 PM
But seriously. As long as the float heights are OK.
But if the tang is damaged. Or twisted it could make sealing difficult
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Post by: Nurse Julie on April 08, 2019, 05:57:41 PM
Reminds me of a song. Tangs for the Memory.Oh my goodness John, that is terrible ;D ;D ;D ;D ;D :-* :-*
Post by: Bryanj on April 08, 2019, 05:58:50 PM
Post by: Nurse Julie on April 08, 2019, 06:07:00 PM
That one seems at more of an angle than"normal" JulieThanks Bryan, I may try and reduce the angle somewhat.
Post by: Raymond_Y on April 08, 2019, 06:43:18 PM
Post by: Nurse Julie on April 08, 2019, 07:08:54 PM
Is it possible that as the float moves up and the tang contacts the valve, that a slight sideways load is being applied to the valve as the valve is actually contacting the slope of the bent tang, canting it in the valve body very slightly. If that is the case it will never shut off. I have stripped quite a few carbs over the years and have never seen a float with anything but a flat tang.I've stripped loads of SOHC carbs and I dread to think how many sets Trig has done but it was the acuteness of the angle that drew my attention to it. We have a huge box full of floats here all from Keihin SOHC carbs and all the tangs have a bit of a bend in them. You could be right, maybe the float spring is slipping off the tang a little bit, if the tang has a slight twist on it, it would make sense.
Post by: Moorey on April 08, 2019, 08:38:27 PM
Post by: Nurse Julie on April 08, 2019, 08:50:17 PM
One of mine on the 350 looked like that.Did you flatten it out a bit Chris?
Post by: deltarider on April 08, 2019, 08:53:59 PM
Post by: Moorey on April 08, 2019, 09:45:39 PM
One of mine on the 350 looked like that.Did you flatten it out a bit Chris?
No I just set the float height to it.
Post by: Nurse Julie on April 08, 2019, 09:47:18 PM
Yes, that's what i did. ThanksOne of mine on the 350 looked like that.Did you flatten it out a bit Chris?
No I just set the float height to it.
Post by: Moorey on April 08, 2019, 09:51:22 PM
Or rather I should say I checked the float height and it was ok with it bent like that so I left it as it was.Yes, that's what i did. ThanksOne of mine on the 350 looked like that.Did you flatten it out a bit Chris?
No I just set the float height to it.
Post by: Nurse Julie on April 08, 2019, 09:53:02 PM
Yep, in my case 22mm is 22mm regardless of what shape the tang is in 😀😀😀Or rather I should say I checked the float height and it was ok with it bent like that so I left it as it was.Yes, that's what i did. ThanksOne of mine on the 350 looked like that.Did you flatten it out a bit Chris?
No I just set the float height to it.
Post by: Moorey on April 08, 2019, 10:02:12 PM
I would have thought so the measurement is taken from as soon as the spring loaded end of the needle touches the tang I believe.Yep, in my case 22mm is 22mm regardless of what shape the tang is in 😀😀😀Or rather I should say I checked the float height and it was ok with it bent like that so I left it as it was.Yes, that's what i did. ThanksOne of mine on the 350 looked like that.Did you flatten it out a bit Chris?
No I just set the float height to it.
Post by: Raymond_Y on April 08, 2019, 10:05:43 PM
Post by: Nurse Julie on April 08, 2019, 10:17:36 PM
From an engineering perspective, a curved tang just does not feel correct, although that is not to say it won’t work. But if there is a problem, then the curve in the tang, and how it works with the valve could be a contributing factor. As someone said earlier, the brass parts of the float assembly I believe were stamped and that would produce a flat tang. However, what is not broken does not need fixed.This is obviously the main difference between an Engineer and a Nurse. A Nurses favorite saying is ' Don't try and fix it if it's not broken fully, you will only make it worse' 😀. I'm thinking that as long as the tang is not twisted from one side to the other and the tang is set right to give me 22mm float height.....its doing its job.
Post by: Moorey on April 08, 2019, 11:01:53 PM
Post by: Nurse Julie on April 08, 2019, 11:17:39 PM
Post by: matthewmosse on April 09, 2019, 08:15:29 AM
Post by: Raymond_Y on April 09, 2019, 10:11:30 AM
Post by: paulbaker1954 on April 09, 2019, 12:54:52 PM
Twice I have bench tested with fuel only to put them back on bike and one of the sodding things would overflow again.
In the end i replaced with ones from Cruzinimage and things have been OK since then