float level tube test

[jjz28]

So, i did the tube test on the 1100 and 1 one was about 1/4 inch below the other 3. #4 got to the same height as 2 and 3 but it took longer to get there. 1,2,and 3 filled right up and 4 was just a little slower. What does this mean. I need to adjust 1's float height and whats the deal with 4.

[jjz28]

By the way, carbs were on the bike and gas was coming from tank and petcocks in there stock position mounted on bike.

[JeffH]

Did the engine have any previous Idling or Acceleration or Backfiring issues? 1/4" off sound whacky since tolerances are +- 1mm on float height. When I checked mine #1 and #3 seemed to fill much slower than #2 and #4 although with the T feed you would think gas would flow unrestricted into both carbs equally from each T. Having a small fuel tank with on-off valve positioned above the carbs would provide better gravity feed and ensure adequate fueling to all 4 carbs.

On my bike it looks like the fuel level is about 1/2" lower than the top of the bowl (where the gasket is). Runs great, Idles good, Plugs are clean and 35mpg on flat tires on an 11E. I might bring the fuel up 1 mm higher in the bowl next time I have the carbs off just to try a change.

Jeff

[JeffH]

By the way, carbs were on the bike and gas was coming from tank and petcocks in there stock position mounted on bike.

OK, on the bike. Was the bike on the Center Stand and on a level surface?? Are you sure fuel was flowing out of the petcock?

Jeff

[jjz28]

Fuel flow was good, bike was level side to side with ratched straps since i dont have a center stand. Yes the bike has a stumble down low and also up really high in the rpms (dont know how high, tach dont work) but it still runs good to me, cause i have never had this much power. The carbs are just bench synced by eyeball too. Also, my fuel level looked to be all the way to the top of the bottom of the bowl, almost where it goes together. Maybe 1 is right and the other 3 are high since yours are down about an inch. I know mine are far from an inch from the top of the bowl.

[jjz28]

So, do i need to lower my fuel levels? I have my floats set at 1". I know that #1 is lower fuel level, should i lower it or put the rest at its level since my other levels were basically at the top of the bowl? How full should the bowls be? I am meetin xsive biker for a ride today and would like to adjust it before then. The only sooty plug was #4 but i adjusted the mixture screw and its better now. The other plugs still looked almost new ( I've only ridden about 60 miles since new plugs). Any help would be appreciated.

[JeffH]

Float Buoyancy & Spring

So, do i need to lower my fuel levels? I have my floats set at 1". I know that #1 is lower fuel level, should i lower it or put the rest at its level since my other levels were basically at the top of the bowl?

Fuel level at the very top of the bowls isn't right. Gas at the very top of the bowl is very close to the level where raw gas would be running out into the Air Box or into the Intakes. The bowls are approx 2" high. The Main fuel pickup feed is about 1 3/4" measuring from the top of the bowl and the Idle circuit pickup is about 1 1/2" from the top. If the bowl is in-fact 'full of gas' -and- the floats were carefully set at 1" then there is another cause.

Were the Floats OK?? Were the Needle Springs OK?? If your Floats are not adequately Buoyant then bowl fuel level would be higher. Same if L or R sides of a Float are not in line. Could have similar effect from bad Needle springs that will not seat properly closing off the fuel at the Spec 1" Float Height. The 25.7mm +-1mm or 1" is static, dry setting. When throwing in additional factors such as grams of lift in Float Buoyancy plus Spring resistance in the Needle then that is more of a dynamic real world indicator of where the fuel actually is in the bowl vs the vacuum differential created by the CCV carb.

Here is a pic of the Floats out of the 78' 11E I am working on. You can definitely see how the dent in #4 is impacting buoyancy. You can also see across a Float that the L and R were not aligned. You can see Float #3 is certainly more buoyant than the others. Also had 1 broken and 3 weak Needle springs. Replaced Needle & Seats plus 2 of the Floats. One with Dent and One with side collapsing. BTW, went I removed the air box I did find there had been a brief 'flash' fire in there from the PO. Bike started ok with these problems but idle was crap and rpm was all over the place. So was header temps.



I'd recommend checking the Floats and Needles next since you are sure the Float Height was already set at 1". Hope you had a nice ride today!

Jeff

[jjz28]

it seems everytime if them back from being dry (after working on them) they will flood out and then i move the bike and peck a little and they dont flood anymore. I am going to check them with them off the bike so i can see better. I have to replace 2 jets so the carbs are off now.

[GLoweVA]

I found a paragaraph in one of my manuals that talks about the clear tube float level height check.

10. After the carburetor assembly is level, hold
the loose end of the tube up against the No. I
carburetor body. Check the fuel level in the
tube. It should be 0.12 +/- 0.04 in. (3 +/- 1
mm) below the top surface of the float bowl
(Figure 12).

So that gives us a spec, but I guess each bike may have a different 'sweet spot'
The key here is consistency across all 4.

[JeffH]

I found a paragaraph in one of my manuals that talks about the clear tube float level height check:
It should be 0.12 +/- 0.04 in. (3 +/- 1
mm) below the top surface of the float bowl
(Figure 12).

Good Info! Thanks for locating the data.
So then, if I have new OEM Needles and Seat with the Floats carefully set and verified at 25.5 mm, the resultant (measured) fuel level was 10mm below the top of the bowl.

That kind of throws out the meticulous need for 25.7mm +-1 on the floats. That has been my issue/point of interest as some struggle with their bad running machines. Actual variations in float buoyancy is then also a factor. 25.7mm (for my 11E) is then just a guideline because it is a DRY / Static setting. If my 25.5 mm Float level resulted in fuel -10mm below the top of the bowl then the issue would be the correlation between Float height (measured) and Float buoyancy (unknown variable) to actual bowl fuel level created by any particular float height setting. When I take the Carbs off for to replace the cracked Intakes I will change the Floats setting to 24mm to see how many +mm that represents in actual fuel in the bowl. The -10mm that I got with 25.5mm setting may be a bit low, but yesterday rode a sporty 130 miles in North Georgia including some twisty's @ 37mpg and motor was running awesome -great power roll-on and good roll-off. Just flawless performance

BTW, I recall seeing someone post recently that they were using 24mm setting on a E or F with brass float because carbs/plugs/engine seemed to perform well with that setting. It would be interesting to get some other feedback on this issue that impacts performance (zoom-zoom) and safety (air box fire).

Jeff

[bikerphil]

I found a paragaraph in one of my manuals that talks about the clear tube float level height check.


So that gives us a spec, but I guess each bike may have a different 'sweet spot'
The key here is consistency across all 4.

That spec IIRC is for the 81-82 carbs, I wouldn't use that spec for the early brass float type carbs, JMHO

[GLoweVA]

Right Phil, I forgot to mention that paragraph from the manual was in the back/supplememt for the 80/81's. (81's have the drain port on the bottom of the bowls)

My basic point is that all 4 should be the same and somewhere close to the top of the bowl. Too high and overflow, too low and engine starves.

[1fasttrucker]

i did the float test also

Hi guys I did the float test discrubed in my clymers manual for the kz 1000 I had my carbs were mounted to a board with the rubber intakes and carefully leveled , my float levals were at the very bottom of the float gasket all 4 carbs across the board, every thing inside the carbs is new every thing , I spent hours makeing shure the floats were set correct,

so what I am affraid of is the gas level in my bowls is to hi , I just caught a 78 1100 E on fire and it was a hell of a mess , should I remeashure my floats and try the float level test again ? the levels show in the book to be right at the bottom of the float bowl gasket !!

[GLoweVA]

The biggest thing I like about this type of float check is you get to see exactly how high the level is and as a bonus, you get to know 100% that the fuel will shutoff before putting them back on the bike. (thus no overflow into the engine/airbox)

I would think that if they are too high, you'd run rich and you'd see that in the performance/mileage.

Again, I don't think there's any hard set "spec" on the height this way, just that all 4 are the same. Each bike's setup (filter/pods/exhaust/driving habits) are going to dictate how high/low you want to set it to.

[DGXSER]

honestly, I have set up a number of 81 carbs and never used the fuel tube method. I put them at 23 +/- .5 mm (the spec for the 80-81 carbs), and button it up. IMO, you can spend the hour or two to meticulously set all the float levels exactly even using this tube method, then go to the end of the driveway and lean the biek to turn onto the road and you just threw all that evening out stuff right out the window. Every curve and start/stop speed up, slow down, moves the fuel around in that bowl.

being an engineer, I tend to be anal retentive about things like this, but experience has taught me that these carbs will run just fine with the settings I use.