Topic: "clear tube" float height method with 657a carbs?

[dave500]

its not truly critical,when your riding the bike leaning and hard accellerating,braking and cornering over rough roads etc the inside of your beautifully set up float bowls looks like the inside of a washing machine on heavy duty cycle anyway,try riding your bike and holding a glass of water stable,,err make mine beer.

[brewsky]

its not truly critical,when your riding the bike leaning and hard accellerating,braking and cornering over rough roads etc the inside of your beautifully set up float bowls looks like the inside of a washing machine on heavy duty cycle anyway,try riding your bike and holding a glass of water stable,,err make mine beer.

Very true.

On my 305, a 2mm difference in float level translated to 0.5 difference in measured A/F reading while riding.

Not that significant unless you suffer from OCD!

[aperry]

Thanks guys, I agree with everything you've said.  I just didn't know why this method for float high measurement was being attacked by certain people.  Seems like it's fairly unwarranted.

FWIW, in HondaMan's book it's mentioned that each 1 mm away from the 26mm measurement corresponds to roughly a 1% change in the A/F mix, which is also roughly a 1 step size difference in the main jet size, through majority of throttle.  Depending on how you interpret it all, I would say it's consistent with Brewsky's findings.  Good to know it has a fairly subtle impact on bike performance, because it's not exactly a precision tuning mechanism!

Thanks a lot guys,
Aaron




 

[lucky]

Yes it is true that A/F measurements may not differ much.

 The real importance of getting the float measurement set is you do not want it too high, spilling over into the overflow or flooding the engine.

You also set the floats to make sure it is high enough to prevent a jet from picking up fuel when needed.

It still needs to be set properly.

Also I do not attack anyone or anything, I just give my opinion and experience.
You obviously can choose to ignore it completely.

[aperry]

Well I guess we can just agree that your definition of "attacking" a methodology is probably different than mine. 

You like to use capital letters and exclamation points to emphasize that people shouldn't ever use the clear tube method for setting their float level.  To me, that sounds like an attack on the clear tube as a methodology for setting float height.  But maybe it's just your writing style, or maybe I'm off base with my definition of "attacking".  Not entirely important to me, but I apologize if I'm in the wrong here.
 

[bollingball]

I removed a float, let it float in a jar of gas, and marked the gas level on the side.

Then installed, set height to spec, and measured the mark distance from the bowl joint.

Turned out to be about 5mm below the bowl joint. (This measurement is for 78 750 K8, and not nesessarily the same for other carbs)

If you ride the bike with the clear tubes attached, you will notice the level stabilizes and may be different than when parked, engine off, and on the sidestand.

Some of the early Honda shop manuals mention a design value for the distance between the fuel height and the bottom of the carb bore, but I've never found that value listed anywhere.

Brewsky I'm not sure what you are doing here. I have the same bike with the 42b carbs When I first set mine up I got #2 float set perfect at 14.5mm then hooked up the clear tube and found the fuel level to be real close to 3mm below the the top edge of the bowl. On these bowls there is a flange at the top and it just happen to measure 3.23mm so the level falls at the bottom of this flange at 14.5mm float height. I find my plugs a little rich at idle (110 jets) pilot screw (1.5 turns out) and read some where you can move the level up or down a little and lean this out but can not remember which way to go. Could not get it lean enough with pilot screw Anyone remember? Might try some (105s) I have. The bike runs good I just want the plugs as clean as I can get them They look great at all other throttle positions.
Ken
See edit I got my jets mixed up I ment to be talking about my slow (35) jets instead of my 110 (high) jets Thanks to Flybox for pointing out my error Been in the shop to long.

[flybox1]

Hey Ken.  Smaller mains probably wont lean you out at idle, but they'll sure change your current plug readings in other throttle positions.
I've got my floats set up at 15mm.  I actually set the height the same as the height as the top of the press in pilots.  1&4 were right about 4mm checking with the clear tube. fuel screws out 1 1/6ths turns.
Plugs are a nice chocolate, and I have 120 mains. 
No burble during idle, and minimal popping on decel.  I probably could dial a little leaner, but i'm happy with it for now.
See my sig below for the other details.

[bollingball]

Hey Ken.  Smaller mains probably wont lean you out at idle, but they'll sure change your current plug readings in other throttle positions.
I've got my floats set up at 15mm.  I actually set the height the same as the height as the top of the press in pilots.  1&4 were right about 4mm checking with the clear tube. fuel screws out 1 1/6ths turns.
Plugs are a nice chocolate, and I have 120 mains. 
No burble during idle, and minimal popping on decel.  I probably could dial a little leaner, but i'm happy with it for now.
See my sig below for the other details.

Sorry Fly I got mixed up I meant my slows (35) I need a break. and they are new oem my old ones looked a little reamed out so I thought that was why I was rich and got new ones. I would think I could dial this in with the pilot screw. Like I said I think I need to take a break and look at it later I start getting things assbackwards like main and slow jets and it just gets worse. Now where is that Jim Beam I will check out your sig thanks
Ken

[flybox1]

I do prefer a little Booker's when musing carbs and jetting...

[brewsky]

I removed a float, let it float in a jar of gas, and marked the gas level on the side.

Then installed, set height to spec, and measured the mark distance from the bowl joint.

Turned out to be about 5mm below the bowl joint. (This measurement is for 78 750 K8, and not nesessarily the same for other carbs)

If you ride the bike with the clear tubes attached, you will notice the level stabilizes and may be different than when parked, engine off, and on the centerstand.

Some of the early Honda shop manuals mention a design value for the distance between the fuel height and the bottom of the carb bore, but I've never found that value listed anywhere.

Brewsky I'm not sure what you are doing here. I have the same bike with the 42b carbs When I first set mine up I got #2 float set perfect at 14.5mm then hooked up the clear tube and found the fuel level to be real close to 3mm below the the top edge of the bowl. On these bowls there is a flange at the top and it just happen to measure 3.23mm so the level falls at the bottom of this flange at 14.5mm float height. I find my plugs a little rich at idle (110 jets) pilot screw (1.5 turns out) and read some where you can move the level up or down a little and lean this out but can not remember which way to go. Could not get it lean enough with pilot screw Anyone remember? Might try some (105s) I have. The bike runs good I just want the plugs as clean as I can get them They look great at all other throttle positions.
Ken

Ken,
The point of the float experiment was to show, with the clear tubes, where the actual fuel level shoud be visually.

It is an approximation, since the actual submerged level is hard to read due to the surface tension warping the intersecting surface.

The error is probably a couple of mm either way.

The most important value to me of the clear tube method, is to determine if all the fuel levels end up being the same after making the adjustment.

I have found that after meticulously setting the 4 floats the same (or so I thought), the resulting fuel level of one or more carbs would end up being slightly different (a mm or 2 off).

I will then ride the bike with the tubes still attached, and see if after stopping, they are still off, and if so, tweak the float that needs adjustment.

I consider this exercise a form of "balancing" similar to vacuum balancing the carbs.

It is also one symptom of "obsessive carb disorder"

I have a Dynojet A/F meter installed so I can see the effect of jetting, needle, intake and exhaust changes as they are done.

[lucky]

I would never try to set float levels with the carbs on the bike.

[lucky]

Well I guess we can just agree that your definition of "attacking" a methodology is probably different than mine. 

You like to use capital letters and exclamation points to emphasize that people shouldn't ever use the clear tube method for setting their float level.  To me, that sounds like an attack on the clear tube as a methodology for setting float height.  But maybe it's just your writing style, or maybe I'm off base with my definition of "attacking".  Not entirely important to me, but I apologize if I'm in the wrong here.

I use capitols sometimes to emphasize a point as if I was talking.
I am not angry. Sorry for the confusion. I will not use capitols from now on unless it is my Birthday !! Lol..lol

[aperry]

Truce Lucky.  Truce!

I'll tell you, I wish the floats had a set screw, or something more precise than a bendable tang.   You know, for those of us with obsessive carb disorder.   (I like that term!)

[dave500]

it would be great if like older holley you could adjust them on the fly with the engine running,i can adjust type one floats on the 500/550 without removing the carbs,cant this be done on the 750s?i thought youd have slightly more room under the carbs between the top of the case?

[brewsky]

It can be done on a 750, especially if all you need to do is tweak one or two to match the others.

[aperry]

On the fly with the engine running?  Yikes.  Sounds hot and messy.  Put a drip pan under the carb, remove the bowl, let the carb drip all over your hand while you remove the float, adjust the tang and reinstall it, trying not to burn yourself?  Something like that?

 

[dave500]

you have to bend the tang in situ,youll be forever trial and erroring otherwise,if you havent tinkered with holleys its no big deal adjusting the float on a live engine aperry.

[chewbacca5000]

aperry,

I have been through this whole clear tube dance myself, and like you it was an overflow tube that initiated it.  What I found is this having float needles of the same strength with a good float gauge makes this a relatively easy process. I should know as I have set them at 24, 25, 26 just to see how the bike would respond.

26 is the only setting that allows the choke to work properly on the majority of carbs.  I like 25mm, but have to crack throttle ever so slightly to get the correct a/f for the bike to start.  If I remember 24mm was soggy.

I then would check with the tube each time to see how far it was from the float gasket.  For every millimeter it would add or subtract around 2 to 2 1/2 mm of fuel in the bowl.

I gave up on the tube and just use it to check my work.

[dave500]

set them mechanically as per factory and thats that,done,dusted,over,finished.,did i mention too easy?

[aperry]

Chewbacca:

Quick question:  Are you adjusting the tang with the float still attached to the carb (using screwdriver or something), or are you removing the little float pin and taking the float out?  When setting between 24, 25, 25 did you remove the carb rack each time, or did you do it "in situ"?

Also, I'm confused about your comment "for each mm it would add or subtract around 2 to 2 1/2 mm of fuel in the bowl".  If the clear tube level goes up or down 1mm, doesn't that mean the bowl level is going up or down exactly 1mm as well?  Maybe I misinterpreted your comment?


Dave:
Yeah, I'm beginning to think you're right.  However I just want to make sure I understand the details here, because adjusting the tang is kind of a clumsy process IMO.  Not sure I'm even doing it right.  Seems like adjusting it by an imperceptible amount translates to several mm of height change.  Are you guys using the gauge to "force" the tang into position somehow?

Thanks guys, good thread, I appreciate all the feedback.

Aaron 

[Rookster]

With the carbs on the bench it is much easier than with them on the bike.  You only use the gauge to check the height.  If you lay the carbs down on the bench just enough to have the float tip toward the needle, adjustment is pretty easy.



If it needs adjusting you just rotate it back and bend the tang then re-measure.  The key is to let the weight of the float rest against the needle without depressing the plunger.

Scott

[bollingball]

I have a Dynojet A/F meter installed so I can see the effect of jetting, needle, intake and exhaust changes as they are done.

Brewsky Got a link for this gizmo? How much are they is that a brand name/
Thanks
Ken

[chewbacca5000]

Chewbacca:

Quick question:  Are you adjusting the tang with the float still attached to the carb (using screwdriver or something), or are you removing the little float pin and taking the float out?  When setting between 24, 25, 25 did you remove the carb rack each time, or did you do it "in situ"?

I pulled the carbs each time and set with a float guage and adjusted the tang on the float.


Also, I'm confused about your comment "for each mm it would add or subtract around 2 to 2 1/2 mm of fuel in the bowl".  If the clear tube level goes up or down 1mm, doesn't that mean the bowl level is going up or down exactly 1mm as well?  Maybe I misinterpreted your comment?

Very simply 24mm means more fuel in the bowl and more in your clear tube.  At 27mm your bike might not start or run very lean at 24mm your bike will be on the rich side and may leak on the side stand.  You want to go with 26mm to start and see where your at.

Aaron

[aperry]

Thank you Chewy!

[brewsky]

I have a Dynojet A/F meter installed so I can see the effect of jetting, needle, intake and exhaust changes as they are done.

Brewsky Got a link for this gizmo? How much are they is that a brand name/
Thanks
Ken

Ken,
The model I have is the Dynojet Wideband Commander.....I think it retailed for 399 or so at the time it came out, but they have come down now with competition. I got a deal on it from a local dealer going out of business, and couldn't pass it up. There are other competitors, Innovate is one that comes to mind, as well as others.
Some more info in this thread.
http://forums.sohc4.net/index.php?topic=107406.0
Here"s another version:
http://www.aemelectronics.com/wideband-air-fuel-systems-15/digital-wideband-air-fuel-gauge-25/