Set the Float Levels on QuickSilver

[V7Goose]

Today I decided to pull the carbs on my 05 RSV and check the float levels. My plugs looked perfect before I touched anything, so that doesn't sound like it was running rich. However, I ran down to Galveston and back yesterday (650 miles) and the chrome tips of my pipes collected a lot more black soot than I like. Even though my gas mileage is still running right where it always has (averaging 36 - 38), I decided to check out the float levels before my next big trip. I first tried the tube method to check the level while they are on the bike, but it just didn't seem to be working right or even close to an accurate way to measure them. So I bit the bullet and tore into it - BIG job to pull that danged carb assembly out!

 

I was quite surprised to find that although all four carbs had the floats set very close to each other, they were WAY off the spec. Where the manual calls for .32 - .36", mine were all at either .133 or .285 (depending on how they were measured). That means the float level was set VERY high.

 

And now to discuss the right way to measure the float height. The drawing in the shop manual clearly shows a carb being held upside down with the float bowl gasket surface level and the float height being measured with a caliper held vertical. Seems straight forward, no? Done that way, mine measured .133" instead of .34". The instructions even clearly state to "hold the carburetor upside down." But then the next thing is this NOTE:

"The float arm should rest on the needle valve without depressing it."

 

Now that is a difficult thing to do with the carburetor upside down; the weight of the float fully compresses the spring loaded plunger in the needle valve. When you lay the whole carb assembly flat on the bench, the carbs are already inclined quite a bit, but even then the weight of the float is still too much for the needle valve spring:

[ATTACH]19149[/ATTACH] [ATTACH]19147[/ATTACH]

 

Sooooo, I propped one end of the carburetor assembly on a short 2x4 so that the face of the float bowl was almost vertical. When you raise the end of the assembly high enough you can see the float suddenly pop up from the spring pressure of the needle valve. Here is a picture of the carb assembly propped up and one of measuring the float height in that position:

[ATTACH]19145[/ATTACH] [ATTACH]19146[/ATTACH] [ATTACH]19148[/ATTACH]

 

I used this position to set all for floats at the mid point of the spec - .34" Bike ran great when I got it all back together, and the sync on the carbs was not changed by the procedure. I only put about 30 miles on it tonight, so I may not be able to report on the effect to my MPG calculation until I get on the road to Ontario next week. But I'll let y'all know how it changes, if at all.

Goose

[Freebird]

All of mine were high the first time I checked them also. I wonder exactly what affect that has on how the bike runs and performs? I know that mine runs much better now but I did so many things, I'm not sure what the affect of this was.

 

It is a fairly big job but is much easier the second time. It will probably be a LONG time before I pull mine again though.

[V7Goose]

Well the good thing is that I had the bike in perfect sync and it was running great for the run down to Galveston. I spent most of the time at an indicated 84MPH (actual 77MPH), and my fuel mileage at those speeds ran from a low of 31 while fighting a big head wind to a high of 36 with that wind behind me. These have always been typical numbers for me when running that fast. Changing the float levels and rechecking the carb sync is the ONLY change I have made to the bike other than normal service before I leave next week, so any significant change I detect in performance or fuel mileage will have to be related to that.

Goose

[Longball75]

Thanks so much for your post you have know idea how much this forum has helped with all the maintenance issues. One question, how do you adjust the float heights is there a screw adjustment. Thanks any help would be greatly appreciated.

[Squeeze]

Thanks so much for your post you have know idea how much this forum has helped with all the maintenance issues. One question, how do you adjust the float heights is there a screw adjustment. Thanks any help would be greatly appreciated.

 

No Screw for the Float Height. You have to bend the Tab on the Floater which connects the Floater Valve.

[Snaggletooth]

I need to ask this..... On a 1st Gen, '84, I rebuilt the carbs due to a problem with flooding. The issue was the floats were sinking on me. The bike had been stored for 9 years when I bought it. Know the floats were the problem and no longer available, I bought a used set of carbs and stripped out the floats and hung them out dry. When they were dried out I coated them with airplane dope, a light coat, to reseal them. When I did the rebuild I swapped out the floats and checked the fuel level. It was extremely low before and it did increase somewhat but does not come up to specs. I have bent all the tangs to the point where I have no room left before the floats hit the inside of the bowl body. I'm still about a 1/4 inch below where I want the fuel level to be. I figure the weight increase from the dope coating is the cause of this.

 

Know the floats that came out of the carbs were culprit in the past problem, am I nuts to consider trying them again after hanging out to dry for a month or so? Any other ideas?

 

One of my creative minded buds wants to sand down the float bodies to reduce the weight and seal again. He's recovering nicely from the lump on his forehead. Reducing the bouyant mass to reduce weight isn't the answer on this one I'm sure.

[Squeeze]

The 1 Gen Floaters are available. If you can't catch some, use them from the Vmax. '85 Vmax had the same Carbs, the later were 35mm Carbs which are the same in that Matters.

Edited June 29, 2008 by Squeeze

[Cougar]

Mr Bird.. Can you add this to the tech libriary? maybe in two places?

ONE in under carb removel.....

 

And it's own seprate section as well. I went throught

that last year and talked about how far my floats were

off after I checked them.. Mr Goose's pictures and on

how he explians it is excelant. I had no idea at first

on how to adjust then but ended up doing it like he did.

 

The manual does not explian this very well..

thanks,

Jeff

[Cougar]

BTW, Did I say EXCELANT WRITE-UP?

EXCELANT!

[Freebird]

Thanks for the suggestion. I copied it to the tech library but only to one place as a new entry.

[V7Goose]

Hey Don, didn't you say you have a ColorTune? Might I prevail on you to drag it up to the rally in Ontario? I'm going to buy a low-end exhaust gas analyzer after I get back, but I'd love to see how the ColorTune works and what it shows about the current mix right now. And if it shows we should make some changes, that will allow me to compare MPG numbers on the way home against the ones I get on the way up there. Thanx

Goose

[Freebird]

No problem. I'll put it out now so that I don't forget it. Old age is a terrible thing.

[V7Goose]

For anyone following this thread, I updated the original article in the tech library with the results from this float adjustment. I won't put all the details here, but suffice it to say that it made a very significant improvement in the fuel mileage on my 05 RSV! If you are one of the owners who can't understand why their miles per gallon don't measure up to what others claim, I would strongly suggest you check your float levels.

Goose

[Rick Butler]

Hey Kent,

 

Are you back yet? I'm interested in taking a look at your gas analyzer after you get it up and tested out. It would be a perfect excuse to come over for a visit.

 

Rick

[V7Goose]

Naw, I'm still in the Frozen North, but after seeing the ridiculous prices for beer up here, I won't be hanging around too long!

 

The possibilities for comments about passing gas and sniffing are just tooo many, so I'll leave that lay for now! Looking forward to seeing ya eventually!

Goose

[Tom]

Naw, I'm still in the Frozen North, but after seeing the ridiculous prices for beer up here, I won't be hanging around too long!

 

The possibilities for comments about passing gas and sniffing are just tooo many, so I'll leave that lay for now! Looking forward to seeing ya eventually!

Goose

 

 

Goose may have to come up that way and buy you alot of beer and see if I can talk you into doin mine sometime..or come to the hill country and free place to stay and all dinners on me! My mileage has dropped and I do not think I am good enough to do te floats myself..It may be I have been a little harder on the throttle lately. Tom

[RPG]

If I don't have raw gasoline running out of my carb overflows I don't understand how float level adjustment would have any effect on my gas mileage? Isn't the float just basically an on/off valve between the fuel pump and the carb? To low and the motor starves for fuel, to high and raw fuel is fed to the bowl faster than the motor can burn it resulting in excess fuel running out the carb overflow hoses. The jets control fuel mixture, not the floats, at least thats what I've been led to believe.

[Squeeze]

The Height of the Fuel Level is significant for the Fuel Consumption. That's just because of plain Gravity Force.

 

The Higher the Float sits, the higher the Level in the Carb Bowl, the higher the Level, the more Fuel is in the Jets. More Fuel in the Jets without any Vacuum Force needed to suck it into the Carb Throat, means more Fuel than needed is sucked into the Motor. Rich Mixture at any State below Full Throttle means less Mileage.

[RPG]

The Height of the Fuel Level is significant for the Fuel Consumption. That's just because of plain Gravity Force.

 

The Higher the Float sits, the higher the Level in the Carb Bowl, the higher the Level, the more Fuel is in the Jets. More Fuel in the Jets without any Vacuum Force needed to suck it into the Carb Throat, means more Fuel than needed is sucked into the Motor. Rich Mixture at any State below Full Throttle means less Mileage.

I don't think so, the over flows shouldn't let the fuel get above a certain point inside the carbs. I had a needle stick a few years back, the engine ran completely normal but gas was flowing out my overflow line by the air filter. If you had a hole in your gas tank and then plugged it you would get better mileage after plugging it, its somewhat the same analogy, if your float is to high your lossing gas, but not through combustion, to remove your carbs just to check your float levels in the hopes of increasing your mileage doesn't make sense, unless your lossing gas out of the overflows. If you have to remove the carbs to clean them or perhaps replace the needle & seats then by all means checking the float levels and adjusting if required would be wise.

Edited July 9, 2008 by RPG

[jneed53]

Goose -- I'll pitch in with Tom if you can let me see how it's done. Never been good with carbs.

[az1103]

Today I decided to pull the carbs on my 05 RSV and check the float levels. My plugs looked perfect before I touched anything, so that doesn't sound like it was running rich. However, I ran down to Galveston and back yesterday (650 miles) and the chrome tips of my pipes collected a lot more black soot than I like. Even though my gas mileage is still running right where it always has (averaging 36 - 38), I decided to check out the float levels before my next big trip. I first tried the tube method to check the level while they are on the bike, but it just didn't seem to be working right or even close to an accurate way to measure them. So I bit the bullet and tore into it - BIG job to pull that danged carb assembly out!

 

I was quite surprised to find that although all four carbs had the floats set very close to each other, they were WAY off the spec. Where the manual calls for .32 - .36", mine were all at either .133 or .285 (depending on how they were measured). That means the float level was set VERY high.

 

And now to discuss the right way to measure the float height. The drawing in the shop manual clearly shows a carb being held upside down with the float bowl gasket surface level and the float height being measured with a caliper held vertical. Seems straight forward, no? Done that way, mine measured .133" instead of .34". The instructions even clearly state to "hold the carburetor upside down." But then the next thing is this NOTE:

"The float arm should rest on the needle valve without depressing it."

Now that is a difficult thing to do with the carburetor upside down; the weight of the float fully compresses the spring loaded plunger in the needle valve. When you lay the whole carb assembly flat on the bench, the carbs are already inclined quite a bit, but even then the weight of the float is still too much for the needle valve spring:

[ATTACH]19149[/ATTACH] [ATTACH]19147[/ATTACH]

 

Sooooo, I propped one end of the carburetor assembly on a short 2x4 so that the face of the float bowl was almost vertical. When you raise the end of the assembly high enough you can see the float suddenly pop up from the spring pressure of the needle valve. Here is a picture of the carb assembly propped up and one of measuring the float height in that position:

[ATTACH]19145[/ATTACH] [ATTACH]19146[/ATTACH] [ATTACH]19148[/ATTACH]

 

I used this position to set all for floats at the mid point of the spec - .34" Bike ran great when I got it all back together, and the sync on the carbs was not changed by the procedure. I only put about 30 miles on it tonight, so I may not be able to report on the effect to my MPG calculation until I get on the road to Ontario next week. But I'll let y'all know how it changes, if at all.

Goose

 

 

I believe you are puting a bit more meaning into the phrase than intended; I grew up in "the age of carburators". Granted, mostly in cars, but a good number of bikes too.

Generally, that just means flip the thing over and let it rest on the needle with its own weight which just overcomes the spring. The reason it is stated that way is the black, hard rubber tip on some (though not all) needles. They don't want you to compress that tip in any way. The problem with not allowing the weight of the floats to overcome the spring is that you can end up with floats being adjusted too low. That can, under sustained load conditions, cause momentary fuel starvation and surging. You would most likely feel this under acceleration and particularly a climbing long turn.

You decide to pass someone, twist hard and stay on the throttle, you surge forward but then feel a power drop or hesitation because the level was too low to start with , then it picks up again. When you first twist hard the accelerator pump injects fuel and depletes the bowl and the sustained throttle doesn't allow the level to restore fast enough.

But that would be the only time you feel it. It has absolutely no effect on your gas mileage unless one of your carburators is so low that it's constantly running lean which will cause overheating of that cylinder and a most likely barely perceptible power loss.

[V7Goose]

If I don't have raw gasoline running out of my carb overflows I don't understand how float level adjustment would have any effect on my gas mileage? Isn't the float just basically an on/off valve between the fuel pump and the carb? To low and the motor starves for fuel, to high and raw fuel is fed to the bowl faster than the motor can burn it resulting in excess fuel running out the carb overflow hoses. The jets control fuel mixture, not the floats, at least thats what I've been led to believe.

I am going to make a lot of very generalized statements here to describe a carburetor and how it operates, so please nobody jump down my throat for detailed inaccuracies! If you think I am just dead wrong, then by all means jump in and correct it, but do understand that I am trying to convey concepts for the average reader, not exact technical details. Also understand that there is a big difference between a needle valve and a float valve, but our shop manual calls the float valve a needle valve. A needle valve usually sticks into the main jet and meters the fuel flow through the jet by how much the carb slide opens. A float valve just closes the fuel flow into the float bowl. For the discussion below, just know that all of it is focused on the float valve, no mater what the manual calls it!

 

Why does the float level affect fuel mileage (and how rich or lean the mixture is)? It is because a carburetor operates on a vacuum. As the intake air rushes through the throat of the carb and into the cylinder, the effect of the air rushing by the fuel ports creates a vacuum that pulls the raw gas out of the float bowls, through the main jets, and into the throat of the carburetor. This is called the "venturi affect". The size of the main jet primarily controls how much gas can be sucked out into the intake by this vacuum, but the level of the fuel in the float bowl also has a big impact. The closer the fuel is to the main jets (the higher the floats are set), the easier it is for a slight vacuum to suck the gas up through the jets; therefore, high floats do cause a rich mixture. The other comments above about possible fuel starvation if the floats are set too low are also accurate, but only come into play if the float level is WAY too low.

 

Now, I cannot speak so adamantly about the meaning of the words in the manual to not have the float "depress" the needle valve. Many needle valves have both a neoprene or nitrile rubber tip to ensure they close completely (older designs just use a smooth metal cone on the end of the valve), and a spring loaded plunger that rests on the float tang, so that the rising float first pushes the valve into the seat very gently. As soon as the valve closes completely, the pressure stops pushing any harder against the valve. If the valve is slightly damaged for any reason, the rising fuel level causes the float to push harder against the plunger, eventually overcoming all of the spring pressure to push directly against the valve, forcing the rubber tip into the valve seat until it completely shuts off the flow of gas into the float bowl.

 

All of that is a factual discussion of how the floats and float valve work. But I cannot swear that my method to adjust them without the spring plunger being depressed is correct. BUT, here is the kicker: If you decide to adjust the float while the carburetor is completely upside down and the valve spring is fully depressed, then setting it to the specs in the manual will set the fuel level MUCH LOWER than the way I did it! If anything is going to starve the engine for fuel under hard acceleration, this will do it (but it probably will increase fuel mileage even more than my adjustment did). Here is why - with my setting, I assume the valve will completely close as soon as the float tang begins to push against the valve spring. If I were to set it with the spring fully depressed, it assumes the valve will completely close only after the float rises high enough to fully depress the spring and then push directly against the valve. If it closes with less pressure (before the spring is fully compressed), then the fuel level will be much lower because the valve will close sooner.

 

I am going to have to do a lot more research (and possibly testing on my own bike) before I can definitively state which method is absolutely correct. In the mean time, I chose the intermediate method that left the float level possibly a bit higher only because I could not believe that it would be right to make such a MAJOR change in the float levels from the way it came from factory to the way it would be set if the floats depressed the plunger springs.

 

I hope that helps some,

Goose

[Squeeze]

I don't think so, the over flows shouldn't let the fuel get above a certain point inside the carbs. I had a needle stick a few years back, the engine ran completely normal but gas was flowing out my overflow line by the air filter. If you had a hole in your gas tank and then plugged it you would get better mileage after plugging it, its somewhat the same analogy, if your float is to high your lossing gas, but not through combustion, to remove your carbs just to check your float levels in the hopes of increasing your mileage doesn't make sense, unless your lossing gas out of the overflows. If you have to remove the carbs to clean them or perhaps replace the needle & seats then by all means checking the float levels and adjusting if required would be wise.

 

The Overflow is sitting so high this is only for Emergency Purpose.

 

A correct Float Level will ensure the proper filling of the Bowl at any Circumstances and it will provide the proper Environment which all Jet Dimensions are adjusteted to. These is for both, Fuel Jets and Air Jets. Main or Pilot Jets, fixed or exchangeable Jets.

 

I'm sorry, but if you believe it or not, i can't think of explaining the Function in an other Way.

 

Only Thing i can add, the Sizes of the Jets sure adjust how much Fuel or Air goes through them, but the Amount of Fuel which is actually going a Jet is under Influence of the Speed the Fuel travels and the Amount of Pressure which is operating this Flow. With a High Fuel Level the positive Pressure (by Gravity) is higher in the Float Bowl. If you put Vacuum on the other Side of the Jet, more Fuel is moved through the Jet on the same Amount of Vacuum. These Differences are very small, but nevertheless this adds up on the Fuel Consumption and Throttle Response. Pegscraper once wrote about a Car Engine which sucked Fuel through the Main Jets on Idle, because the Factory has had the Idle Circuit on the Carbs too lean.

[RPG]

The Overflow is sitting so high this is only for Emergency Purpose.

 

A correct Float Level will ensure the proper filling of the Bowl at any Circumstances and it will provide the proper Environment which all Jet Dimensions are adjusteted to. These is for both, Fuel Jets and Air Jets. Main or Pilot Jets, fixed or exchangeable Jets.

 

I'm sorry, but if you believe it or not, i can't think of explaining the Function in an other Way.

 

Only Thing i can add, the Sizes of the Jets sure adjust how much Fuel or Air goes through them, but the Amount of Fuel which is actually going a Jet is under Influence of the Speed the Fuel travels and the Amount of Pressure which is operating this Flow. With a High Fuel Level the positive Pressure (by Gravity) is higher in the Float Bowl. If you put Vacuum on the other Side of the Jet, more Fuel is moved through the Jet on the same Amount of Vacuum. These Differences are very small, but nevertheless this adds up on the Fuel Consumption and Throttle Response. Pegscraper once wrote about a Car Engine which sucked Fuel through the Main Jets on Idle, because the Factory has had the Idle Circuit on the Carbs too lean.

I agree with your first two sentences, the over flow is set for emergencys like a stuck needle valve and I certainly agree that its important to have the float level set correctly in order to prevent fuel starvation or fuel loss through the overflow. Sorry though, your last paragraph is just just nonsense.

[Squeeze]

I agree with your first two sentences, the over flow is set for emergencys like a stuck needle valve and I certainly agree that its important to have the float level set correctly in order to prevent fuel starvation or fuel loss through the overflow. Sorry though, your last paragraph is just just nonsense.

 

Nonsense, eh ??

 

OK, you're right.:bowdown::bowdown: