Topic: 77 CB750A float height

[evopgt]

Hi All. I’m working on assembling the CB750A carbs.  It’s a 1977. The manual states that float height should be 12.5mm. It just doesn’t look right.  The flat bottom is angled at a measurement of 12.5mm at the main jet.  Does this pic look correct?

[scottly]

It's been a loong time since I played with stock carbs, but are the floats upside-down??

[evopgt]

No, that’s how they are supposed to go in.

[Medyo Bastos]

Check in the garage~>


http://www.hondachopper.com/garage/carb_info/carb_info.html




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[evopgt]

That article is saying they set all the pd carbs to 14.5.  So maybe I’ll just set to 14.5.  They would be level then.   

[Medyo Bastos]

Doggy is a great guy. Stop in and give him a shout when you get yourself back on the road!


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[evopgt]

We’ll, I checked my clymer manual, It states differently than the Honda manual. Honda says 77-78 models should be 12.5mm while clymer says CB750A models should be 14.5mm. I’m going to set them at 14.5mm then do a clear tube test before initial start up to assure fuel levels are 3-4mm below body-bowl gasket.  Thanks guys

[rotortiller]

You might want to look at the various float part numbers. 78K item and 76A are different PNs than the 77K and 77A/78A models. Respectively they have different shared float height specs.   (16013-KCY-670 or 16013-405-004)     iF the carbs have not been bastardized I would trust Honda data as the PNs  and maintenance specs agree.

44Bs are off a 1977A model which means  12.5mm is the published spec. 14.5 is for 78k and 76A models. Want to verify go here  13-1. http://manuals.sohc4.net/cb750a/service_manual/SM750A.pdf

If it were me I'd take one carb and verify the fluid level on the bench with liquid before the assembly and install of the rack.

[05c50]

You probably already know this but the assembled height of aftermarket float valves and the oem valves are not always the same. After installing aftermarket valves, I had to make (what seemed like) drastic adjustments to the floats to get the proper fuel level.

........Paul

[evopgt]

I am going to do a clear tube test after setting the floats to the 12.5mm float height and see what I get. When you guys say appropriate bowl fuel level. What exactly is that? How high On the bowls, in comparison to the fuel in the clear tube should the fuel level be??

[evopgt]

Bump.. Anyone know where the fuel level should be in relation to the bowls for the clear tube test?

[05c50]

After setting the float level as per the FSM, the fuel level was about 2 mm below the float bowl gasket line.

..........Paul