Float Level measure with 'tube tool'

[armyofda12mnkeys]

I've always measured float level with my electric caliper correctly based on reading many threads here (making sure to measure it from the inside of the carb where the gasket is placed as recommended here ),
but I thought I'd grab this tool I saw a couple others on the forums got or made to see if my float measurements are really correct...
http://www.ebay.com/itm/like/271428570431?lpid=82&chn=ps

Anyway here are pics of carb with the tool below and wondering if any of these look like they can be modified slightly.
Where should the gas level be reaching (maybe someone can Photoshop the level to easier identify it for others as well)?

One carb's gas level is between the top of the float bowl and the bottom edge of the top
(makes more sense with the pics below what i define as the 'between both edges area'):

The other carb is at the bottom of that edge of the float bowl:

Thanks for any direction!,
Ari

 

[16VGTIDave]

That is how DOHC floats are checked. On them, the stock fuel height is 3mm +/- 1 below the float bowl sealing surface. With the gasket installed, carbs perfectly level, etc. Much more accurate than setting a float height by measuring its dry resting position and hoping it "floats" the same as its partner.

 

[armyofda12mnkeys]

oh mine is a 1978 XS400E, which is a SOHC (not DOHC).
I just assumed I could use the 'tube tool' on it. Technically why couldn't you use that tool?
Doesn't it serve the same purpose in measuring where the gas would get stopped by the float?

Im wondering if I can use it still on the SOHC Mikuni BS34 carbs, then where 3mm would be since I dont know where the gasket sealing surface starts (unless I take off the float drain bowl and measure it then put the float bowl back on, mark it off on the drain bowl somehow (or eyeball it), and do the same tube test).
Think 3mm would be closer to the 1st or 2nd pic?

 

[16VGTIDave]

Sure you can use the tube method! You measure down from the mating surface of the float bowl, when assembled correctly with the gasket in place. The paper float bowl gasket is almost 1mm thick, so it must be installed to get an accurate measurement.

If I had to guess, I'd say the 2nd pic is close, except I'm not seeing the gasket installed...

What I've done, is to put 2 marks on my tube that are 3mm apart. The top mark gets aligned with the top of the float bowl and the bottom mark is where the fuel level should be. Easy as that.

 

[XSLeo]

Setting the float height is critical, it determines the fuel level in the float bowl. This fuel level effects how rich or lean the carbs run. To low a level is lean, too high is rich. The floats are a metering device, not a shut off.
Using the float measuring method gets them very close. As 16VGTIDave said it works well if the floats both "float" the same. If one float is heavier than the other. the fuel level may be effected.
The tube method lets you see the actual fuel level. And you can set them to match much closer than by measuring.
The +or- 3mm is not so much a tolerance side to side as from rich to lean. I would try to get both floats set the same. You can use float height to adjust for lean or rich by altering the height the 3mm +or-. More than that it will effect jetting. If you go too much one way you may need to go up or down on the pilot jet.
When adjusting measure both sides of the float. The metal bracket between the two bulbs can be bent enough to throw off the setting. Lets say the metal is bent and you measure just one side and get the 22 m or what ever is speced and the other side is at say 18 mm, as the floats "float" the actual level will be half way between.
In your pics I think the second pic is right. I'm not sure on the BS34's, but on the XS650 the early repair manual shows a cutaway of a BS38 carb with the tube hooked up. It shows the level as 4 mm below the gasket surface of the carb body. That would put it about where your second pic shows.
I would set both carbs to match, ride it a few days watching how it runs. Then try the other setting and see how the change effects things.
Leo

 

[Robsteeler66]

Do you need two of the tubes, or can you just use one and then switch it to the other side.

 

[armyofda12mnkeys]

Rob: I would assume 1, otherwise the seller would say you need to buy 2 and make 2x profit .
My carbs were at different levels since the gas level in each carb is operated independently by each separate float.

Thanks everyone, I'll try setting each carb soon.
PS i assume pushing the float's tang lower, it would then touch and engage the float pin earlier when the gas is rising in the bowl.
and once it touches that float pin, it then would turn off the gas flow into the carb.
so more obtuse angle = less gas in bowl.

and the gas level goes higher if the float tang becomes more flatter.

I dont think anyone would have the float pin actually above the base float level since that would I guess float the carb with way too much gas.