Carb fuel level. Help

Hi, I'm setting the fuel level on my xj700x, the manual is not very clear on where to check the fuel level on Mikuni carbs. Should the level be measured up to the carburettor body as in example A (red) or should it be measured down to the gasket contact surface as in example B (green)?

My specification is 3mm +/- 1mm

 

Hi, Check my video as it should answer your question...

 

Here’s the write-up.....

http://www.xj4ever.com/setting fuel levels.pdf

 

Damn, good question.
I have always gone by the side of the carb, In your picture 'A'.
Pretty that is correct.
and, more importantly, it works for me!

 

After reading over and over again, I came to the conclusion that the correct place to measure is from B.

The manual says:



And I think the bottom edge of the carb body is where the gasket is.

I hope I'm not wrong.

 

Did you read this? If you did you would have seen this:

 

The gasket is on the top edge of the bowl......the top edge of the bowl and the gasket both sit up into the bottom of the carb body a little bit. That’s why we use the visible bottom edge of the body as a reference point——-since we can see that.

 

I'm confused again, are you telling me that the correct place is A in my image?

I read your manual and saw that the bowl and gasket sit up into the bottom of the carb body, but my carb is different than the carb on your manual.

On my carb you can see the gasket.



The difference between A and B (top of the bowl) is a little more than 2 mm.



I guess another way of looking at things is that the fuel level should be 3mm below the top of the bowl, that's why I'm measuring from B. But I don't know if I'm wrong or right.

 

Did you read the PDF?
Did you read the PDF?
Did you read the PDF?
Did you read the PDF?

MEASURE FROM THE BOTTOM OF THE CARB BODY

MEASURE FROM THE BOTTOM OF THE CARB BODY

MEASURE FROM THE BOTTOM OF THE CARB BODY

MEASURE FROM THE BOTTOM OF THE CARB BODY

 

Bump. Shows where to measure from on the x

 

measure from the green part

 

Ok, that's a clear answer. Just to satisfy my curiosity, where did you find the information that this is the point to measure from? I don't doubt you knowledge of course

 

? maybe chacal, maybe hogfiddles, rick-co-matic or bigfitz, it's been awhile

that's your first mistake

 

Hahaha, thanks!

 

Make sure your not measuring from the top of the ridge though..... you need to measure from the FLAT part

 

One topic solved! Though it might have been clear for some before now there is no question about it anymore.
Thanks all for thinking with me on this one.
Carbs have to come off again...

 

So Polock is saying "B" - wow that was hard.

So the PDF for wet setting is incorrect then because it shows the measurement from the bottom of the lip - unless you consider x-ray vision and someone is measuring to a point of reference they can't see?

In the thread - https://xjbikes.com/forums/threads/what-is-correct-float-height.129499/

MrSeca asked:

"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?"

jayrodoh replied:

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

So no one saw the need to correct jay? Perhaps because he was correct in his response?

Are all the factory service manuals wrong, as they clearly show the measurement being done from a visible point on the carb, the bottom of the skirt? They did get the reference designator wrong for "4" and "5."

XJ700N Air Cooled HSC-33



So the lip / skirt on the Hitachi carb is about 2mm tall, does anyone really believe that an error of 2mm will affect the performance of the bike? Say for example, if wet set 2mm low making it lean would you speculate that the pilot mixture screw would go from 2 turns out to 4 turns out to compensate for the low fuel level?

 

This is about the carbs for the X, there Mikunis BS33.
They have a lip on the corners and sides but not on the front and back of the carbs so the bottom of the body is visible to measure from.
For the Hitachis I believe you measure from the bottom of the lip of the carb body.

 

Today I've set the fuel level all to 3-3,5 mm below the carb body (green flat part in the last pic posted). Start great and idles steady without choke after 1 to 2 minutes. Didn't have a change to take her for a ride yet.

 

Yeah, it's a pity this simple answer wasn't given before, would have saved me time. On the other hand people are trying to help others selfless and that's a great thing on this forum.

 

So from the X FSM:



Fuel Level a: bottom of meniscus to bottom edge of the carburetor body 3.0 ±1.0 mm (0.12 ± 0.04 in)


Common sense doesn't always apply, but when all the FSM's talk about doing this on the bike they instruct you to use the outside carb side for the inner two. That makes sense as the side is impossible to get to on the bike for two inner carbs, and the back is nearly impossible. I certainly wouldn't want to try to get my hand and face in there to measure at the back of two and three. And, you top that off with any tilt from front to back is negated when you measure on the side in the center of the float chamber, as instructed and depicted in the FSM picture.

And yea, for the Hitachi particularly the 700N with the 1mm spec it would require some x-ray vision or some premeasurements to use point "B."

 

Well the FSM photo first led me to measure from the side of the body as you describe. The drawing in the FSM on the other hand doesn't match reality with the carbs on the X. So they made it very confusing. Another thing that we don't mention when we're talking about wet setting the fuel level is that the FSM says you have to start the engine and let it idle during the measurements. Doesn't this affect the readings?

End of the story is I rely on those of us who set the levels with good results in the past. My own findings are that the bike seemed to run lean before and that seems better now. But as I said, still have to take her for a ride.

 

True, but after leveling the bike/carbs from side to side and front to back both readings A and B are possible. If B is correct than the manual is wrong?

 

Good job guys, but logic tells me that the bowl holds the fuel were trying to set the level of, so the bowl mating surface is most accurate to measure for a fuel level float. Sorry if I come off as an a$$, not my intention.

But I have one for ya..... Is the gasket being taken into account. You will gain slight height.
A paper gasket can smash to about 1mm, and rubber ones can be as thick smashed to about 1.5mm to 2mm, so if the desired set height is to be 17.5, or the (I heard/read ) factory set is 21.5
Your measurements will be off.

May be a little over kill in thought, but that's just how I roll. Lol

 

the gasket has nothing to do with it

 

Correct, because you measure from the carb body. So no gasket or an inch thick gasket makes no difference, just changes the volume of fuel in the bowl. Yeah, I've learned something here

 

Took a while but finally had the time for a long 3 hour ride. First last week I did final adjustments to the idle mixture related to the spark plugs color. After that a running sync again. Bikes starts with little choke (temp 68 °F), idle is steady after a few minutes and stays steady at 1050 rpm also after fast (90mph) ride. Bike responds very good over the whole power band and pulls strong from 7.000 to 10.000 rpm. Very, very satisfied with the settings now.