Author Topic: Brass and Plastic Floats  (Read 1548 times)

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Offline M.Harrigan

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Brass and Plastic Floats
« on: November 07, 2013, 10:05:43 AM »
I hate to add another "Float Thread" but I could not find the answer to this question.
I am rebuilding a set of carbs that I bought but have never used.
The set has 2 plastic and 2 brass floats. Is it ok to have mixed floats or do they all need to match?

Offline 750K

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Re: Brass and Plastic Floats
« Reply #1 on: November 07, 2013, 10:14:07 AM »
I would have no problem mixing, as long as the brass were in good shape and not leaking. After all it's the float level that is more important as far as I'm concerned but I've been wrong befor lol.
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Offline flybox1

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Re: Brass and Plastic Floats
« Reply #2 on: November 07, 2013, 11:05:00 AM »
I would have no issues either, but...if all were set with the same float height, the fuel levels might be slightly different between the brass and the hard foam because of buoyancy differences.
the only way to verify you have the correct fuel level for the carbs you are running, is with the clear tube method.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

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Offline 70CB750

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Re: Brass and Plastic Floats
« Reply #3 on: November 07, 2013, 11:19:10 AM »
2 years ago I soldered on of my floats because it was leaking.  The weight difference was 10 grains or so, it works fine ever since.

That said, I don't think it matters significantly how heavy/buoyant the float is.
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Offline flybox1

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Re: Brass and Plastic Floats
« Reply #4 on: November 07, 2013, 11:36:59 AM »
6/10ths of a gram is minute.  But however minute, any deviation from stock and there will be a change.
Might not matter that much in your case as all your floats were the same.
In this case, the floats are different (shape, weight, volume, displacement) and need to be treated as such to yield the same bowl fuel level across the carbs.




'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline Vinhead1957

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Re: Brass and Plastic Floats
« Reply #5 on: November 07, 2013, 12:31:57 PM »
I also have had leaky brass floats. I think ethanol likes those solder joints.   I prefer the plastic ones because of this.

Offline lucky

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Re: Brass and Plastic Floats
« Reply #6 on: November 07, 2013, 04:11:49 PM »
I hate to add another "Float Thread" but I could not find the answer to this question.
I am rebuilding a set of carbs that I bought but have never used.
The set has 2 plastic and 2 brass floats. Is it ok to have mixed floats or do they all need to match?


NO... do not mix them and use the right ones. Unless you like lots of problems.
Of course they have to match!  Cheeeeesssshhhh!!!!



Offline lucky

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Re: Brass and Plastic Floats
« Reply #7 on: November 07, 2013, 04:13:12 PM »
I also have had leaky brass floats. I think ethanol likes those solder joints.   I prefer the plastic ones because of this.

The plastic floats have foam inside.

Offline ekpent

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Re: Brass and Plastic Floats
« Reply #8 on: November 07, 2013, 04:49:09 PM »
I replaced the bad brass floats on my K1 with 4 used plastic ones and have never looked back, one less thing to go wrong.

Offline Kevin D

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Re: Brass and Plastic Floats
« Reply #9 on: November 07, 2013, 06:23:49 PM »
I have 3 brass originals and 1 plastic replacement for about the last 10 years and 20000 miles.. or so.
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Offline Don R

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Re: Brass and Plastic Floats
« Reply #10 on: November 07, 2013, 06:53:51 PM »
 As long as the fuel level is set the same the carbs don't know. Heck they're not even speaking to each other.
No matter how many times you paint over a shadow, it's still there.
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Offline flybox1

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Re: Brass and Plastic Floats
« Reply #11 on: November 07, 2013, 09:23:13 PM »
As long as the fuel level is set the same the carbs don't know. Heck they're not even speaking to each other.
^this
Proper fuel level is the goal. Clear tube method will show you the way.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline 70CB750

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Re: Brass and Plastic Floats
« Reply #12 on: November 08, 2013, 03:07:00 AM »
As long as the fuel level is set the same the carbs don't know. Heck they're not even speaking to each other.


 ;D
Prokop
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I love it when parts come together.

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CB750K3F - The Red
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Offline Johnie

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Re: Brass and Plastic Floats
« Reply #13 on: November 08, 2013, 04:54:18 AM »
On my first KO 3 of the 4 floats were leaking. Changed over to plastic. On my current KO 2 of the 4 were leaking. Have already switched those over to plastic. My own view is 40 year old brass floats have seen their life. Change them out unless you are one who likes to run stuff until it dies.
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Offline Don R

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Re: Brass and Plastic Floats
« Reply #14 on: November 08, 2013, 05:48:56 AM »
 New floats are nice, I'm putting them in one set of my carbs.
I've given up on old float valves. The new ones in my 76F are sweet. If I forget to turn off the gas, no more stinky or exploding garage.
« Last Edit: November 08, 2013, 05:53:44 AM by Don R »
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
 You don't need a weatherman to know which way the wind blows.