What is CORRECT float height

I'm looking for the EXACT, DEAD ON BALLS ACCURATE place where the float height is suppose to be. I've been reading way too much about float height and plenty of people explain it but don't SHOW it and the old manual is a little hard to understand.

Referring to the picture below is the float height suppose to match the red, green, or yellow dot?

 

You are refering to fuel height. I would say the green (top) dot. Looks like you're using Mikuni carbs there. Here is a section of the wording from the Haynes FJ1200 manual. The FJ uses Mikuni carbs.
Whenever i set the float height i just set the floats until fuel stops pouring out of the jet holes in the carb mouth. Anyway...here

WP_20201204_08_56_19_Pro_LI[1] by Billy Bananahead, on Flickr

Ooops, that's big.

 

I never read this page before, on my bike I can't get the carbs vertical without removing the rear tire while the bike is on the center stand.
It also says to checked the float level of fuel at the top in the hose on this page, it's my understanding it's at the bottom of the curved level of fuel in the hose.

 

Fuel levels are set with the carbs on the bench, not in the bike.
http://www.xj4ever.com/setting fuel levels.pdf

 

Jeeze. Everywhere I post this I'm getting different answers. No wonder setting these levels are confusing.

 

The level of fluid in a tube is always set to the bottom of the meniscus, for the sake of consistency.
That's an industrial standard.
Whether Yamaha decided to go against that, is another matter.

 

You can measure the levels with the carb on the bike, it just has to be level and usually means putting bike on the center stand and possibly some wood under a wheel. Good luck adjusting them on the bike though, waaaay easier on the bench.

With the carbs level, the fuel level should be ~3mm from your green dot. +/- 1mm is okay but I shoot for 3.

Correct, liquid in a tube creeps up on the sides, the bottom of that curve is called a meniscus.

 

Sorry If I'm making this more complicated but one thing to add, never pull the hose upwards when checking the level. The fuel will go back into the bowl and since the valve is closed it will raise the fuel level shown artificially. I like to lower the hose a little once the fuel rises up and stops.

 

I would like to know for Mikuni AND Hitachi since I have both. Please don't include pictures of old manuals. They are not helpful. If you know FOR SURE then please tell me red, green, or yellow for either Mikuni, Hitachi, or both.

 

From the green dot on both.

Levels from Chacals catalog:

Fuel Level Cheat Sheet:

Here's the proper fuel-level settings by model when using the "clear-tube" method of measurement:


Hitachi all HSC32 series models:

NOTE: all of the following models used HSC32 carbs:
XJ650 Maxim, Midnight Maxim, XJ650RJ Seca (non-turbo), XJ650 Euro all use HSC32 carbs (various versions)
XJ750 all USA 1981-83 models use HSC32 version 5G200 (Seca) and 15R00 (Maxim and Midnight Maxim)
XJ750 all Canadian 1981-83 models use HSC32 version 5H200 (Seca) and 15T00 (Maxim and Midnight Maxim)
XJ750 UK/Europe 11M models, XJ750 Police models 24L and 37H use HSC32 version 5N100

-Fuel level measured via the clear-tube gauge: 3mm +/- 1mm (.12 +/- .04 inches)

-Float height: 17.5 +/- 0.5mm


Hitachi HSC33 series (XJ700 air-cooled models):

-Fuel level measured via the clear-tube gauge: 1.0mm +/- 1mm (.039" +/- .039")

-Float height: 16.0 +/- 1.0mm


Hitachi HSC33 series (XJ750E-II model):

-Fuel level measured via the clear-tube gauge: 5.0mm +/- 1mm (.197" +/- .039")

-Float height: unknown


Hitachi HSC33 series (XJ750RL models):

-Fuel level measured via the clear-tube gauge: 1.0mm +/- 1mm (.039" +/- .039")

-Float height: unknown, but possibly the same as XJ700 air-cooled models (16.0 +/- 1.0mm)


Mikuni BS28 (all XJ550 except 1984 XJ550L):

-Fuel level measured via the clear-tube gauge: 2mm +/- 1mm (.08 +/- .039 inches)

-Float height: 21.5 +/- 1.0mm


Mikuni BDS26 (USA all 1992-98 XJ600 Seca II):

-Fuel level measured via the clear-tube gauge:
USA: 4 - 6mm (.016 - 0.24”) below float chamber line

-Float height: 6.2 - 8.2mm (0.24 - 0.32”)


Mikuni BDST28 (non-USA all 1992-98 XJ600 Seca II):

-Fuel level measured via the clear-tube gauge:
1992-96 Canada and Australia: 3 - 5mm (0.12 - .0.20”) above float chamber line
1992-95 UK: 3 - 5mm (0.12 - .0.20”) above float chamber line
1996-98 UK: 8.5 - 9.5mm (0.34 - .0.37”) above float chamber line

-Float height:
1992-96 Canada and Australia: 11 - 13mm (0.43 - 0.512”)
1992-95 UK: 11 - 13mm (0.43 - 0.51”)
1996-98 UK: 8.8 - 10.8mm (0.35 - 0.42”)


Mikuni BS32 (all XJ550L, 1984-85 FJ600, and 1984-87 / 1989-91 XJ600):

-Fuel level measured via the clear-tube gauge: 3mm +/- 1mm (.12 +/- .04 inches)

-Float height: unknown


Mikuni BS30 (all XJ650 Turbo):

-Fuel level measured via the clear-tube gauge: 2mm +/- 1mm (.08 +/- .04 inches)

-Float height: 17.5 +/- 0.5mm


Mikuni BS33 (all XJ700-X and XJ750-X):

-Fuel level measured via the clear-tube gauge: 3mm +/- 1mm (.12 +/- .04 inches)

-Float height: 17.5 +/- 1.0mm


Mikuni BS35 (all XJ900RK/RL):

-Fuel level measured via the clear-tube gauge: 5mm +/- 1mm (.20 +/- .04 inches)

-Float height: 22.3 +/- 0.5mm


Mikuni BS36 (all XJ900F, FN, N, etc):

-Fuel level measured via the clear-tube gauge: 5mm +/- 1mm (.20 +/- .04 inches)

-Float height: 22.3 +/- 0.5mm


Mikuni BS34 (all XJ1100 and XS1100):

-Fuel level measured via the clear-tube gauge: 3mm +/- 1mm (.12 +/- .04 inches)

-Float height:
25.7 +/- 1.0mm (1978-79 all models)
23.0 +/- 0.5mm (1980 all models)
not specified (1981-82 all models)

 

So far you have given me the most straight forward answer. THANK YOU. The clear tube method heights you included, however, are confusing because it doesn't give a point of reference where to measure from.

 

Maybe you’re misunderstanding the process. You don’t set the level to the green dot, you measure the fuel level from it. For example, the hitachi on your Seca 650 should be set to 3mm below that green dot. All those measurements above reference the bottom of the carb base or the green dot in your pic.

 

See the link I posted above. It covers all OEM carbs for all XJ models.

Keep in mind that even the factory service manuals have some errors in them, most of which we know about, but some of which are still new to us here.

 

With all due respect I want to know where you set the level "TO!" Not FROM. TO! The exact point! Also, the carb body LIP "umbrellas" over the bowl and is different then the CARB FACE where the gasket lays against. The green dot is where the LIP is. Which point of reference do I use? But to entertain what you are saying, if the Red dot is exactly 3mm BELOW the CARB FACE, not the LIP mind you, but the CARB FACE, will that be where you set the fuel level TO? Again, I want to emphasize where you set it TO not FROM.

 

Referencing the pic which is a carb bowl from a Seca 650: Since the top of the CARB BOWL rests against the CARB FACE. Would this level be the right point? (see photo)Also, should the absence of the gasket be considered when making this measurement?

 

Make a mark 3mm on the side of your bowl then when they are assembled with a gasket in place. The reason they reference 3mm from the bottom of the carb body is stays constant with the depth of the jet into the fuel. The gasket could be an inch thick and you would still need to set the fuel level 3mm from the bottom of the carb body.

Your pic above would be wrong since it does not include the gasket nor take into account that the bowl fits up into the body.

I get that you want to know where to set it TO, but you cannot set it TO that point without referencing the FROM from the body where the jets are fixed.

 

Thank you for clarifying that, however, you are referring to the "carb body" as the point of reference. Where on the carb body do you measure from? Do you measure from the "carb face" where the gasket rests against OR the "lip" of the carb body that drapes over the carb bowl?

 

Lip over the bowl. Green dot in your first pic.

Quick pic from paint. On the left is a carb with a bowl with no gasket. Here you can see the 3mm fuel level. On the right is the same carb with a thick gasket (indicated in green). You can see why marking the bowl is not consistent, if there was a 3mm mark on the bowl on the carb pictured on the right without a gasket and then you install a gasket, the mark would "move" down and then it would run way too lean as the level would be too low. The depth of the jet tube into the fuel affects how rich/lean it runs.

 

Mr Jayrodoh. Congratulations! You have been the only one to explain this to me in a correct and logical manner.

To summarize: The correct level should be, in this case (Seca 650) WITH the GASKET INCLUDED 3mm +/- 1mm from the bottom or "lip" of the carb body.

It should NOT:
1-be measured from the point on the carb body where the gasket rests against.
2-be measured from the top of the carb bowl.
3-be measured without a gasket

Am I finally understanding this correctly?

 

Logical maybe, but there is plenty of correct info in the links/advice provided before. I basically explained the same thing on top of page 8 but I just went into more detail. I like to understand why and if I can help someone else understand things then cool.

1 and 2 are correct. 3 is not as you can set without a gasket or with three gaskets in there and it won't affect the fuel "level" and only affects the volume. Now if you are going to make a mark on the bowl then yes install your gasket, make a mark 3 mm down and then use that mark to set your fuel level to.

 

you should also check the tide charts for your area and never set during low tide

 

LOL

 

This is a really useful, informative thread, well done contributors all.

 

Teacher hat on:

Most people learn and communicate in a similar way, but not everyone does. Asking for clarity is not wrong, but it can indeed be frustrating when we assume that we have already communicated clearly to begin with. Put aside the assumptions and clarify (as several here have) even when it's frustrating to do so. I'm not innocent of assuming that the learner communicates and thinks in the same way that I do. This thread is an example of humility and perseverance as applied to problem-solving. Well done.

 

As a teacher in the profession myself I have to more often then not create ways to get my student to understand something. I often take for granted the knowledge I have learned and cultivated over the years and expect a student to understand it instantly forgetting the journey I once took to figure something out. In this case I am still the humble student and I am the type of guy to ask the same question probably 3 different times in 4 different ways. But I don't give up and I am always grateful to the people who don't give up on me as well. Thank you everyone. Now time to rebuild some carbs.

 

That’s what we’ve been saying all along

 

What is correct BS30 float bowl volume when drained?

 

What bike?

 

Any bike that takes a BS30. Mine is a Yamaha Turbo.

 

The fuel level can vary based on the application. I don't think I've ever seen the volume measured anywhere. From the archive:

Mikuni BS30 (all XJ650 Turbo): -Fuel level measured via the clear-tube gauge: 2mm +/- 1mm (.08 +/- .04 inches) -Float height: 17.5 +/- 0.5mm

 

But, the cheat sheet says—

 

Rub roh raggy, I got that from the PDF linked in the thread you got that from.

Stick with the fuel level method and you’ll be okay, I think it’s a better way to set it anyway.

 

That’s right off the cheat sheet.

 

Yah I see that, the PDF and the fuel system thread have different specs:

 

Hmmmmm

 

Dave, Remember when you and Len were discussing my Turbo carbs and discovered the error in one of the references you were using? I don't know which one was correct though. I eventually wet set mine and did not measure the float height after.
John

 

I remember, and figured you’d pipe up here

 

@Simmy

or just wet set and be done

 

just rebuilt 4 HSC 32's. the new float needles and seats are much shorter than the ones i replaced. the 17.5 mm dry float levels DO NOT WORK, however, it appears that if your fuel levels were properly set before you replace these, they will still be in the ball park. the parts i was able to get are K&L 10L-14390-02 (18-8937). i don't know what these were set when i dismantled them, they do appear to have been near the 17.5mm (11/16") dry levels.

i guarantee you that if you try to achieve the 'dry' level of 17.5mm, you WILL have problems.

 

If the fuel valves are that different, then I’d question if you have the right fuel valves