Fuel Level - Searched but still don't understand

[cowboyup3371]

I've seen a lot of comments about using a plastic hose connected to the bowl's drain plug to visually check the level of fuel in the bowl. This thread seems to have the best wording http://www.thegsresources.com/_forum...el+level+gauge for me to use to do it but I am having problems visualizing how it's done. I understand I need to connect a hose to the bowl drain plug and then turn up alongside the carb. But I don't understand the following:

Does the fuel continue to flow up the tube and do I need something to catch it before overflowing?

At what point do I shut down the engine to measure what I have or do I shut it down?

Is there anything else I need for this technique?

I also read through my Clymer's manual real quick and don't see a reference to this in there but I could have missed it too.

Thanks for the clarification.

[tkent02]

The fuel in the tube goes to the same level as it is in the bowl, and stays there. Leave the engine idling, look at the level of all four bowls. If there is one that is off from the others, you will see it.

[waterman]

I find it a lot easier to bench check the fuel levels. It may not be as precise since engine is not involved but it is a lot easier to perform and then adjust floats as necessary.

I have used water instead of gasoline and it seemed to work fine. Just need to blow it dry when finished.

[fishfarm]

In my case, I already had the carbs off the bike but connected together, so I mounted the carbs on a wood post over the bench using a couple of nails and leveled the rack. This way I could take the rack on and off the mount to remove/install the bowls and adjust the float tangs easily.

I took the float bowl off one carb and connected the clear 1/4" tube (about 12" long). With the bowl in my hand I could see the tube solidly in the drain hole. Reattached the bowl and found a spot to anchor the tube above the carb flange.

Put fuel in the temporary tank and watched as the fuel rose in the tube and waited for it to settle. (I had marked 5mm below the flange with a piece of electrical tape.) If the level was off, dropped the rack to the bench and adjusted the tang that holds the float needle. Retest/adjust until in spec. I drained the fuel back to the gas can each time by dropping the end of the clear hose into the spout.

I used the bowl with the tube already attached for each carb; just swapped bowls. It's a tedious and time-consuming process even with the carbs on the bench. I'm not sure how you would adjust the levels with the carbs on the bike; maybe someone who has done it can comment.

[850 Combat]

[QUOTE=waterman;1377315]I find it a lot easier to bench check the fuel levels. It may not be as precise since engine is not involved but it is a lot easier to perform and then adjust floats as necessary.

I have used water instead of gasoline and it seemed to work fine. Just need to blow it dry when finished.[/QUOT

That makes sense, but wh
at level are you looking for? What criteria is used?

[tkent02]

I made four drain plugs with tubes attached, bend the tubes around the side of the carbs, up alongside the end float bowl, attach them with a zip tie or something. Then run the engine. If the levels in the four tubes are the same, I'm done. If not, there's more tinkering to do.
One more note, warm the bike up so you can turn off the choke. If the choke is turned on, the levels read wrong.

[chuck hahn]

Fishfarm..the reason they say to do it with the bike running is that as he engine consimes fuel the float have to be set properly to keep pace..They may be fine on your nails but what are they doing in real life with the bike running?? Now do you understand why its to be done that way? And yes it is tediuos..you run the bike..make notes and you may have to pull the rack a few times to get them adjusted. Be sure the bike is sitting level like on the center stand.

[cowboyup3371]

So are the measurements including whatever fuel is in the bend?

Should I make marks starting from the bowl screw up to show 22.4mm?

[chuck hahn]

Go to bikecliffs website and bring up the 8 valve 750 service manual..i saw pics of the way they say to mark the tube there...had just 3 marks..full explanation as to the way to hold it and what the perameters are.

[tkent02]

I don't even bother with marks, just look through the fuel in the tubes to see where the fuel comes up on the side of the float bowl. As long as all four are the same and about a mm below the seam it is working right, but look in the manual to get the correct level for your model. If one is noticeably higher or lower than the others it will stick out like a sore thumb.

[Larry D]

The trick to this is that fluid will seek it's own level. So....the level of fuel in the bowl is the same as the level of fuel in the clear tube. It allows you to "see" what the fuel level is inside the bowl.

[Steve]

I have used water instead of gasoline and it seemed to work fine. Just need to blow it dry when finished.

I guess this is why you are "waterman"?

I would avoid using water, though. The difference in specific gravity between the two fluids will affect how high the floats ride, which will affect the actual level of the gas.

So are the measurements including whatever fuel is in the bend?

Should I make marks starting from the bowl screw up to show 22.4mm?

It does not matter how long the tubing is, but longer tubing will simply have more gas in it when it's time to drain the hose.

The 22.4 mm mark is only when the carbs are dry, open and upside down. When they are full of gas and in operating condition, most of the specs I have seen call for a fuel level 4 or 5 mm below the top of the bowl.

.

[waterman]

I guess this is why you are "waterman"?

I would avoid using water, though. The difference in specific gravity between the two fluids will affect how high the floats ride, which will affect the actual level of the gas.


.

I will admit it has been a few years since I did this and as I think about it you are correct that the water would affect the actual float levels.

If I remember correctly, I was dealing with a flooding KLX carb. I had set floats and it would continue to overfill. As this carb (keihin CVK) had an overflow, I ended up wearing a fair amount of gasoline as I was messing with it. The wife didn't find the gasoline perfume to her nose, so in order to keep Mrs happy (foolish endeavor), I used water.

As I reflect and contemplate the ramifications of the exercise, the floats should have been less buoyant due to higher density of water; hence led to higher actual fuel (water) levels. So when I adjusted the floats to lower the fuel levels it should have been too low instead of overflowing. In the end, I replaced the float valve since it still wouldn't shut off correctly.

Maybe I should revisit this carb and double check it

[Adler]

It does not matter how long the tubing is, but longer tubing will simply have more gas in it when it's time to drain the hose.

Well, that is true in theory, but in reality the fuel will not come up to EXACTLY the same level as in the bowl, it looses some height to little things (like pretty much all physics). I bet that if you had a small diameter tube and you used a meter of it, you'd start to notice a difference.

Of course for our purposes the loss is minimal.

[fishfarm]

Fishfarm..the reason they say to do it with the bike running is that as he engine consimes fuel the float have to be set properly to keep pace..They may be fine on your nails but what are they doing in real life with the bike running?? Now do you understand why its to be done that way? And yes it is tediuos..you run the bike..make notes and you may have to pull the rack a few times to get them adjusted. Be sure the bike is sitting level like on the center stand.

I was fully aware of the difference between the bench set and on the bike running. My experience so far is that the results are satisfactory. Please refrain from snarky comments.