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Offline cb750fbomb

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Float bowl height
« on: March 07, 2009, 12:00:06 AM »
Is it necessary to by a float bowl gauge or is it just to big a pain to do it without one? Any tips on doing this without a gauge if needed? I've searched and have not been able to find anything about this.
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Offline neil10

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Re: Float bowl height
« Reply #1 on: March 07, 2009, 12:34:28 AM »
keep them all the same , measure 26 mm from carb base where bowl lies riler would be ok if u have good eyes
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Offline TwoTired

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Re: Float bowl height
« Reply #2 on: March 07, 2009, 01:23:20 AM »
Fairly easy to make a bowl gauge out of some stiff but "scissor-able" flat plastic.  But, I simply use a pocket ruler with those slide-able "T" clips.

Beware, the PD carbs for 77 and 78 750s do NOT use a 26mm float height measurement.

Cheers,
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Offline cb750fbomb

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Re: Float bowl height
« Reply #3 on: March 07, 2009, 02:18:30 AM »
Thanks guys. I new there was a good way without spending $40-$50 on a gauge. I intend to have the specs for the carbs right next to me when check the height.
Also, do you just set them in a pile of rags or something to balance them? It seems like it will be tricky to get the bowls at the right height if the the carbs are level. Sorry. I'm a newbie.  :-[
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Offline Inkscars

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Re: Float bowl height
« Reply #4 on: March 07, 2009, 07:35:46 AM »
Quote from: TwoTired on March 07, 2009, 01:23:20 AM
Fairly easy to make a bowl gauge out of some stiff but "scissor-able" flat plastic.  But, I simply use a pocket ruler with those slide-able "T" clips.

Beware, the PD carbs for 77 and 78 750s do NOT use a 26mm float height measurement.

Cheers,
Two tired, You said on 77 750 do NOT use 26mm float height, what should I use?
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Offline cb750k7

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Re: Float bowl height
« Reply #5 on: March 07, 2009, 09:21:11 AM »
Quote from: Inkscars on March 07, 2009, 07:35:46 AM
Quote from: TwoTired on March 07, 2009, 01:23:20 AM
Fairly easy to make a bowl gauge out of some stiff but "scissor-able" flat plastic.  But, I simply use a pocket ruler with those slide-able "T" clips.

Beware, the PD carbs for 77 and 78 750s do NOT use a 26mm float height measurement.

Cheers,
Two tired, You said on 77 750 do NOT use 26mm float height, what should I use?

Here from the manual.
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Offline cb750fbomb

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Re: Float bowl height
« Reply #6 on: March 07, 2009, 10:18:54 AM »

Two tired, You said on 77 750 do NOT use 26mm float height, what should I use?
[/quote]
Hi Inkscars.
Not to answer for TwoTired, but our carb set up must be diff. because my bike is an F model where yours is a K.
My carb is a PD41B.  :)

Model    Year Casting#   Float Height
CB750F     77     PD41B      14.5mm

But now I'm confused because:
CB750K  77     41A  12.5mm

http://www.sohc4.net/index.php?title=FAQ#How_do_you_clean_the_float_bowls_and_set_the_float_height.3F
« Last Edit: March 07, 2009, 10:29:52 AM by cb750fbomb »
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Offline cb750k7

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Re: Float bowl height
« Reply #7 on: March 07, 2009, 10:31:03 AM »
Take a look at the manual,  both 77-78  "F" and "K" use 14.5 mm
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Offline Inkscars

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Re: Float bowl height
« Reply #8 on: March 07, 2009, 10:35:09 AM »
I did, thank you both. Hopefully this is my issue and I can stop losing expensive fuel.  ;D
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Offline Spanner 1

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Re: Float bowl height
« Reply #9 on: March 07, 2009, 11:06:28 AM »
Bomb !,
Your float level is 14.5mm ......pd41 b carbs.........cb750 '77.. float is 12.5mm...pd41a carbs. Don't get it about 'pile of rags' ??  Just lay the carb. on its side,i.e. float pivot pin vertical..swing the float towards the the carb. body  ( would be float rising with carb. in stalled on bike ) look at the float valve moving up as to shut off fuel..keep going until pin on bottom is compressed..o.k. now valve is ' home ' in its seat...next, swing float down passed where the tab is not pressing on the float valve pin....then move float back up until the tab JUST touches the valve pin...measure gap at front top of float up to carb. body...front being tip of float furthest from float pivot pin...Got it ?!
Whoops, almost forgot...if not the correct measure ( bet it is as not something that can change by itself, unless a PO messed with it, I digress... )  its then time to very carefully bend the tab up or down very slightly to obtain correct measure. As TT says, cut a credit card to 12.5mm and you can slide it in to check, much easier than a ruler and trying to read it every time. Good luck.  Shoot I meant to say 14.5mm !!!!!!
« Last Edit: March 07, 2009, 11:17:58 AM by Spanner 1 »
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Offline Inkscars

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Re: Float bowl height
« Reply #10 on: March 07, 2009, 11:15:15 AM »
Quote from: Spanner 1 on March 07, 2009, 11:06:28 AM
Bomb !,
Your float level is 14.5mm ......pd41 b carbs.........cb750 '77.. float is 12.5mm...pd41a carbs. Don't get it about 'pile of rags' ??  Just lay the carb. on its side,i.e. float pivot pin vertical..swing the float towards the the carb. body  ( would be float rising with carb. in stalled on bike ) look at the float valve moving up as to shut off fuel..keep going until pin on bottom is compressed..o.k. now valve is ' home ' in its seat...next, swing float down passed where the tab is not pressing on the float valve pin....then move float back up until the tab JUST touches the valve pin...measure gap at front top of float up to carb. body...front being tip of float furthest from float pivot pin...Got it ?!
Whoa.
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Offline TwoTired

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Re: Float bowl height
« Reply #11 on: March 07, 2009, 11:31:07 AM »
zzzzzzzzzzzz.......yawn....
I just woke up.   What did I miss? 
Oh, yes to the 14.5mm float height.  It is measured when the float valve rest on the float valve seat and the bowl tab >>just<< touches the float valve spring pin.  The lowest part of the float S/B @ 14.5 mm.  I think I my F carbs, that was also when the bottom flat part of the floats was parallel to the carb body bowl gasket surface.

But, I guess it's been covered already....


 ;D

Cheers,
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Offline cb750fbomb

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Re: Float bowl height
« Reply #12 on: March 07, 2009, 09:38:21 PM »
I had been told in the past that you have to fill the bowls with gas to check the float bowl height.  ???
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billybobobrain

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Re: Float bowl height
« Reply #13 on: March 07, 2009, 09:46:04 PM »
Quote from: cb750fbomb on March 07, 2009, 09:38:21 PM
I had been told in the past that you have to fill the bowls with gas to check the float bowl height.  ???

You can do it that way to........ If you want to remove the carb 100 times. ;D
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Offline Spanner 1

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Re: Float bowl height
« Reply #14 on: March 07, 2009, 09:47:58 PM »
Ya could, with the clear-tube-connected-to the drainscrew(open)-held-up-past-the-float-bowl-measured-from-gas-level-to-carb.-body-method. Fine, but how does one adjust the level if the prognosis calls for it ?
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Offline cb750fbomb

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Re: Float bowl height
« Reply #15 on: March 07, 2009, 10:17:26 PM »
The no gas method definitely sounds like the way to go and that explanation got a "whoa" from me as well.
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Offline Inkscars

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Re: Float bowl height
« Reply #16 on: March 09, 2009, 05:54:54 AM »
Twotired, I know you can help me. My build thread is under my pic on here or you can search "clambake" It'll prolly come up. I really could use some expertise here. I'm dying.
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Offline cb750fbomb

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Re: Float bowl height
« Reply #17 on: March 09, 2009, 10:36:15 AM »
The heights are all good. $7 ruler with sliding level, kung fu grip. Home Depot  :)
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