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Discussion Starter · #1 · (Edited)
The problem:
Fuel runs out of the overflow pipe on both carbs and defies anything I can think of

The Carbs:
Keihin: with "DK" in raised letters on the carb at the Flange adapter
"B-5" on Flange adapter
carb inlet = 31 mm ID, 35.5 OD
21.5 mm ID of flange adapter
appeared that original carb internals may have been replaced with aftermarket
Main jet = 92 Slow jet = 38

The bike:
1965 CB160 serial number starting with 10,000 -- received bike, engine and carbs in boxes -- disassembled 15 years ago, otherwise a fairly nice bike

What I've tried.

1) Setting float height to 19.5 as per CB160 Honda service manual
2) Setting float height to 21 mm as in CB175 -- (a shot in dark - worth a try)
3) Two different sets of float valves/seats and needles that both say "1.7"
4) With float bowl off and fuel line on, I can lift floats fully and shut off flow of fuel
5) Float bowl gaskets not touching floats
6) Tried two sets of floats -- old set and a new set
7) Held removed float bowl and filled with fuel to check for cracks in over flow tube

Conclusions:
Since both carbs display the same problem, it would seem the problem might be related to the parts used -- but I don't know
If the float valve was longer (stuck down further) the system might work (= ? wrong float valve assembly ???)

Obviously, I need some help because I have exhausted my knowledge :)

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Sensei
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Please phone me .....540-525-5199
 

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Discussion Starter · #3 ·
Steve is always helpful.

Steve suggested to look at several things and mostly ended up suggested looking at the tab on the floats. Should be not bent on an angle that will push float needle sideways enough to bind needle.
I will check again. He also suggested incrementally increasing float height until the valve actually seals.

Told Steve I'm about frustrated enough to just buy new OEMSTD carbs :)
But first ,,,,, I will try putting extra aluminum washers under under float valve to result in it sitting lower in the bowl, check angle on adjusting tab on floats and incrementally increasing float level setting
 

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I have had similar problems when using aftermarket needle valves and seats. They are not machined to the same dimensions as the original parts.
TOOLS
 

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The overflow tubes in the bowl can crack. Check with carb spray. Then clean and solder.

Sent from my SM-J320V using Tapatalk
 

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Discussion Starter · #6 ·
I ordered the OEMSTD carbs and an hour later suddenly saw the problem more clearly (figures :rolleyes: )
The original parts must have (had to have had) had longer needle in the float valve or longer (as to sit more deeply) whole valve assembly -- gotta be it (y) gotta be. Only way it would work with factory spec of 19.5 mm float height.
Bending the tab on the floats far enough to raise float height enough adjustment to the necessary level to shut off the float valve puts the tab at a huge angle -- which Steve suggested I try to avoid

pattyandrick -- thanks, I checked that

Tools1 -- thanks for chiming in, Ol' wise one, but they shut off the fuel flow when I lift floats with my finger and the overflow is not a "drip" , it is a flow
 

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The force you can put on it with your finger is a lot more than the float can apply.
TOOLS
 

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Discussion Starter · #8 ·
Tools1
Thanks for your input
Yes, it would be a greater force with finger -- certainly
But two carbs with two sets of float valves tried in each -- and all 4 samples behaved the same -- Yes, it's not conclusive, could have all 4 valves all a POS but seems a little bit unlikely
 

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Discussion Starter · #9 ·
Well, as Tools1 suggested it might still be the float valve and needle, I tried another float needle and seat (these came out of a working 175 carb) -- same problem with it. That makes 5 sets of float valve needles and seats. -- I just can't see the problem. This problem does not seem possible unless there is something really special about the OEM float valve and this is not the OEM float valve in the carbs (or, maybe my wife is right about me :rolleyes: ).. But I'm a gunsmith and I'm used to working some pretty tight tolerances and identifying problems.

Finally feeling like I'm just wrapped around an axle and that the motorcycle Gods hate me, I put on the new OEMSTD carbs. -- they work fine.
Maybe I will see the problem on another day.

Thanks to all that tried to help me. I know it's tough to help someone diagnose a problem when you do not have the machine in front of you, and I appreciate the efforts. :)
 

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Discussion Starter · #10 ·
ah ha! as we all know, if you leave it alone for a while and come back to it, sometimes you see it more clearly. I was truly wrapped around an axle on this one.Just could'nt see it.

Anyway, just in case someone else runs into this:::::::::::::::::::
it was the dadgummed POS aftermarket new floats. The little brass "shelf" that extendes from the float and contains the "adjuster" and pivot/pin hole came off the aftermarket floats at a slightly different angle. And "slightly different" was enough to make me crazy o_O. Installed old floats after fixing teeny tiny titsy hole and all is well.

Simply did not previously think about the angle the "shelf/platform" coming off the float doing it. Now, it's, oh yes, but of course - that's it! :)
 

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Sensei
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Thanks for posting the solution......This may now help others with similar problems.....:D(y)
 
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