Set the Float Levels on QuickSilver

[RPG]

Nonsense, eh ??

 

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

Come on Squeeze, don't jump on the poor Canadian just because he doesn't agree with you EH!!!

Gossey did a nice article on setting float levels, I'm printing it off and keeping it for reference purposes. I just don't think people should be led to believe or encouraged to delve into a job as involved as that in search of just better gas mileage, thats all. They are more than likely just going to create more problems than they solve. Thats just my opinion though.

[BOO]

Seems to me people that jump into this job without some knowledge end up having to have someone straighten out their mess.

Some things just don't change without a reason and are best left along....don't even ask me how I know this.

Jerry

[V7Goose]

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.

Actually, I think that Squeeze's description is quite accurate - it just deals more with the physics of how the carb works instead of the more simplistic description of only the vacuum affect on the fuel flow that I used.

 

The fact is, changing the float level in a carburetor WILL affect the fuel mixture. I just did not know how much it would change on our bike until I tried it and measured the results. I don't know if mine is right yet, but I have absolutely PROVED that it changed - both by the color of the exhaust deposits inside the chrome tips of my pipes, and by the calculation of fuel consumption before and after the change.

 

I also agree with anyone who says that someone should be cautious before jumping into a mechanical job that is a bit beyond their skill level. But that doesn't mean they shouldn't either try it or ask someone else to do it if they suspect a problem. Everyone has to try something the first time before they can learn how to do it - book learning only goes so far! Just because an engine seems to be running OK is NOT an acceptable reason to leave it alone for me if I evidence that it may not be running CORRECTLY. Once we can validate what fuel mileage you can realistically expect out of this machine, then any bike that is turning in significantly lower numbers is NOT running correctly in my opinion.

Goose

 

BTW - here is a link to a page I found on the web that describes setting the float level in motorcycle carbs. It is not specifically for the RSV, but the concepts are the same. This, along with several other references I found support the method I used in my original post.

http://771doug.netfirms.com/float.html

 

And just for grins, here is a quote copied from a Webber carb manual. Even though this isn't even a motorcycle carb, it still covers the same points about why and how to set the float level:

 

"The float level is a critical part of carburetor calibration. Changing the fuel level in the bowl will change the point that the main circuit starts to feed, alter the characteristics of an emulsion tube, and affect drivability and fuel consumption.

GENERAL INSTRUCTIONS: Float level, in mm, typically refers to the distance from the face of the carburetor top cover to the float. With the top cover held vertically (float pivot at the top) and the float tab (Lc) resting against, but not depressing the spring loaded ball in the needle valve, measure between the face of the carburetor top cover to the top or bottom of the float."

[Squeeze]

Come on Squeeze, don't jump on the poor Canadian just because he doesn't agree with you EH!!!

Gossey did a nice article on setting float levels, I'm printing it off and keeping it for reference purposes. I just don't think people should be led to believe or encouraged to delve into a job as involved as that in search of just better gas mileage, thats all. They are more than likely just going to create more problems than they solve. Thats just my opinion though.

 

I don't know Gossey and i find it very nice when you keep such 'nice Articles' for yourself. That's what the Internet and such Boards are about. To exchange Informations and Opinions.

 

 

What you stated first sure doesn't say anything about what you've 'meant' to say. You stated that setting the Floats at any Point where they're not too low or too high would be good enough as the Floaters are just a fill/stop Switch.

 

If that would be a Fact, Yammi would not insist on accurate Dimensions for the Floater Valves during the Procedure. Not to mention what Goose expierenced with wrong Settings as a Lot of other Guys on a Lot different Bikes and Motors.

[az1103]

Actually, I think that Squeeze's description is quite accurate - it just deals more with the physics of how the carb works instead of the more simplistic description of only the vacuum affect on the fuel flow that I used.

 

The fact is, changing the float level in a carburetor WILL affect the fuel mixture. I just did not know how much it would change on our bike until I tried it and measured the results. I don't know if mine is right yet, but I have absolutely PROVED that it changed - both by the color of the exhaust deposits inside the chrome tips of my pipes, and by the calculation of fuel consumption before and after the change.

 

I also agree with anyone who says that someone should be cautious before jumping into a mechanical job that is a bit beyond their skill level. But that doesn't mean they shouldn't either try it or ask someone else to do it if they suspect a problem. Everyone has to try something the first time before they can learn how to do it - book learning only goes so far! Just because an engine seems to be running OK is NOT an acceptable reason to leave it alone for me if I evidence that it may not be running CORRECTLY. Once we can validate what fuel mileage you can realistically expect out of this machine, then any bike that is turning in significantly lower numbers is NOT running correctly in my opinion.

Goose

 

BTW - here is a link to a page I found on the web that describes setting the float level in motorcycle carbs. It is not specifically for the RSV, but the concepts are the same. This, along with several other references I found support the method I used in my original post.

http://771doug.netfirms.com/float.html

 

And just for grins, here is a quote copied from a Webber carb manual. Even though this isn't even a motorcycle carb, it still covers the same points about why and how to set the float level:

 

"The float level is a critical part of carburetor calibration. Changing the fuel level in the bowl will change the point that the main circuit starts to feed, alter the characteristics of an emulsion tube, and affect drivability and fuel consumption.

GENERAL INSTRUCTIONS: Float level, in mm, typically refers to the distance from the face of the carburetor top cover to the float. With the top cover held vertically (float pivot at the top) and the float tab (Lc) resting against, but not depressing the spring loaded ball in the needle valve, measure between the face of the carburetor top cover to the top or bottom of the float."

 

Now these are statements I can fully back. BTW I actually ran into problems many moons ago following precisely these instructions from Webber (This in the days of heavy competition between Webber and Carter) . I followed their instructions to the letter and ended-up with a surging and bucking engine. I then redid the adjustments inverting against the spring and all went well. Ultimately I got tired of Weber's insane idea of all adjustments by bending links and threw their carb in the garbage. I replaced it with a Carter which I adjusted (or rather checked the adj.) only once. It ran flawlessly for a couple of years until I traded in the car.

[Freebird]

You guys have described all of this pretty well. I'll just add one thing. It was mentioned that they should be OK but every person that I know who has checked these floats have found them to be WAY off. I agree that they probably should not change but either they DO change or else Yamaha was very sloppy when they assembled them. Most people have found that no two are set the same height and MOST are very high.

 

This is NOT a difficult job. A bit time consuming but some of you make it sound like an engine overhaul. I would say that anybody with a mediocre skill level and willing to just take their time can do this with no problem.

[FuzzyRSTD]

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

 

Thanks Goose, I posted my mpg of average 44 (after Roadhouse pipes and K&N filters, blocked AIS) at different speeds. The results from others almost made me think that I had made a big mistake. So I very critically checked again and the same numbers appeared. I even felt as if some thought I lied about it. But it is still 44 mpg. Only time lower is when I get one of those, wonder what 90 mile an hour would feel like right now, and then I think about the wife and kids and return to reality and 55. Thanks for all your work and the good articles.

James

[BOO]

You guys have described all of this pretty well. I'll just add one thing. It was mentioned that they should be OK but every person that I know who has checked these floats have found them to be WAY off. I agree that they probably should not change but either they DO change or else Yamaha was very sloppy when they assembled them. Most people have found that no two are set the same height and MOST are very high.

 

This is NOT a difficult job. A bit time consuming but some of you make it sound like an engine overhaul. I would say that anybody with a mediocre skill level and willing to just take their time can do this with no problem.

 

I pretty much agree but I think adjusting the floats in a carb gets more people in trouble than about anything else they can do to their bike or whatever with a carb on it. If you don't really understand how the measurement is done you can cause yourself a lot of heart ache. Not saying it shouldn't be done once in a while but it's not one of the easier jobs.

On another note, I decided to get my 65 BSA running last night. It had been setting for about 4 years. I took the carbs apart to make sure they were clean and after putting it back together it only took 4 kicks and she fired right up.

The floats on the BSA are plastic, the float needles are plastic and there is NO adjustment for the float level.

Jerry

[Freebird]

Jerry,

I don't remember, have you ever posted any pictures of the BSA? I love those old bikes and would like to see it.

[V7Goose]

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

For Tom and jneed53, and whoever else in this area is interested, I'd love to get together with you and check out the float levels. I think I'd prefer to do it at my place, where I have all my tools (and there are two of us up here already), but I am not opposed to meeting you somewhere else either. I don't charge much for my help - just make sure you got beer! It takes a few hours to do, but as long as I am not the only one twisting wrenches, they can all be done at pretty much the same time. Let's set a date, time and place and get to it!

Goose

[Tom]

For Tom and jneed53, and whoever else in this area is interested, I'd love to get together with you and check out the float levels. I think I'd prefer to do it at my place, where I have all my tools (and there are two of us up here already), but I am not opposed to meeting you somewhere else either. I don't charge much for my help - just make sure you got beer! It takes a few hours to do, but as long as I am not the only one twisting wrenches, they can all be done at pretty much the same time. Let's set a date, time and place and get to it!

Goose

 

Will look at my schedule,Like to do it before I head to Colorado on 8/22/08,but if ,or that may be crowding it..Will let ya know latr in week..Thanks! Yes I will turn wrenches also,I am not afraid of getting my hands dirty,at least I learn something! Tom

[Gearhead]

I just read this whole thread for the first time and have a couple comments.

1. For some reason, floats on cars were almost always measured the way Goose did it, with the carb top inverted and measuring the physical distance. Bike carbs almost always have their primary measurement stated as "fuel level", done with the bike idling and a clear tube next to the carb body. I dunno why the difference, but the latter seems more "to the point" to me, since fuel level is really what we are interested in. You have to be sure to "burp" the measurement tube of air bubbles to get an accurate measurement. That being said, it is interesting, Goose, that you got your mileage up. I didn't look at the other post; can you give a round number something like, you used to avereage, this, now you average this?
   
2. Any float I remember measuring that had a spring plunger in the needle said the same thing in the manual - float arm contacting needle but not compressing spring. However, I seem to remember that the spring is usually stout enough to hold the float up.
   
3. To weigh in on the "fuel level affecting mileage" argument: Are you familiar with the term "hydrostatic pressure"? It's the pressure at the bottom (or at any point, actually) of a body of liquid caused by the weight of the liquid above it. The deeper the liquid, the higher the pressure. It's the reason divers can only go so deep in the ocean, and deep sea subs have super-stout hulls. The higher the fuel level above the main jet, the higher the hydrostatic pressure at the main jet. Fuel flow in a carb is caused by a pressure difference. Airflow through the venturi (throat) decreases the pressure on top of the jet outlet (we call it a vacuum), while atmospheric pressure and hydrostatic pressure together push on the main jet inlet. This pressure difference causes the airflow to "suck" the fuel out. The bigger the pressure difference, the more fuel flows. Higher fuel level causes more hydrostatic pressure on the jet inlet, thus increasing the pressure difference, thus increasing fuel flow for a given amount of airflow in the throat.
   

There's my 2 cents. I feel better now.

 

Jeremy

[V7Goose]

Was about 36 MPG avarage, now about 40 MPG.

Goose

[Squeeze]

Thanks Jeremy, for expressing my Thoughts in a Way better Language than i come up with.

[Gearhead]

You're welcome, Squeeze. You oughta here me describe hydrostatic pressure in German! (NOT)

 

Hehehe...

 

Goose, that's cool, keep us updated as you put on the miles, if that changes. Kinda makes me want to lower all my floats by 1/8"!

 

Jeremy

[V7Goose]

I just did the float levels on a friend's RSV, and this time I noticed that the two sides of the float are different shapes AND different heights! No idea why I didn't notice that before, but it means that you need to be consistent in measuring the same side of the float on every carb. The difference in height between the thin side and wide side of the float is .04", which almost guarantees that one or more carbs will be out of spec if they are not all set using the same side of the float. Since the choke linkage is kinda in the way when measuring on the inside edge of the float bowls, I'm pretty sure I didn't use the same side for all four carbs. Darn! Guess it's time to pull those suckers out and do it again.

 

Anybody want to get together and make a party of it?

Goose

[Gearhead]

Tempting, yes, but a long commute to TX...

 

Jeremy

[wkboard]

When are you going to do it? I can fly to DFW standby, and would LOVE to watch you work, or help. It is difficult for me to get away in Nov or Dec, but I would sure try!

Even if I don't make it, I always enjoy reading your posts, and learning from them. Lots of pictures always helps me learn.

Maybe another southern maintenace day?

Or a southern learn about carbs day?

Go for it Brother-- this sounds better the more I talk about it:thumbsup2:

[V7Goose]

Oh, I don't know when I will do it - I am very flexible on my schedule (can you say "retired"? I knew you could). If someone around here wants to come over I'll try to plan it around their schedule. Since all of these things seem to be so far off from the factory, it certainly isn't critical when I do it! And if you want to fly in, I'll be happy to pick you up at the airport - it's only about 10 miles away.

 

BTW - I'll just note again that when I did my floats the first time I saw an average 4 MPG improvement in my fuel mileage. It is impossible to accurately compare mileage on a motorcycle in only a tank or two since the volumes are so small and the variables are great, but I note and calculate the miles per tank on every gas receipt, so I do get a good average and can absolutely see any change. Moakster has only run a couple of tanks through his bike since we did his, but he says he is seeing a couple of mile increase in his MPG too.

Goose