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Discussion Starter · #1 ·
Tell me if I'm going in the wrong direction...

To adjust the floats on my carbs, while they're still on the bike, I would just push the floats up until the close the valve, but before compressing the spring on the valve. Then I would measure from the base of the carb, where the bowl would meet it, down to the bottow of the float and adjust if necessary. Does this sound right? I think I'm having an issue with my floats, so I bought new valves and was going to adjust them monday after work.

Thanks!
 

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You wrote" I would just push the floats up until the close the valve, but before compressing the spring on the valve."... turn the fuel on, lift float until it shuts off, THEN measure..... Messy, but accurate...Be careful!....do this outside .... Fuel fumes will "roll" across floors and find an ignition source... A neighbor did this back in the 60's and burnt down his house when the fumes found the water heater pilot.....
 

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Discussion Starter · #3 ·
It will be in a garage so I should be good. But I am going for as accurate as possible, so I will try it with the fuel on! Thanks for the response sir!
 

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In my neighbors house (that burned) the bike was in the garage, water heater in basement (off garage)Screen door in between.... Do it in OPEN AIR!!! preferably with a catch pan....and an assistant to turn the fuel on and off....
 

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May i suggest something that will save you a lot of frustration & hassles??
Take he carbs off the bike & turn them upside down. It is much easier and more accurate this way.
You are much less likely to end up with a toasty black bike this way also.
 

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We tried recommending that first.....and, I agree taking them off is much safer...It's also easier if you take the carbs off on a bike that uses screws to hold the bowls......
I do however adjust 450 carbs on the bike all the time, but I use a small fuel supply, do it outside, and the 450 bowls simply snap back on with the bail....
 

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Discussion Starter · #7 ·
Well I adjusted the floats and put on new float valves and no more leakage! Adjusting them while on the bike wasn't all that hard, so that was cool. I had a really small funnel from my nitro r/c cars I used to use a tiny amount of fuel and had a rag under the carbs and a tray under the motor, so no fuel on the ground!

Thanks guys!
 

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To check the float height, make yourself a gauge out of one of those junk credit cards that arrive in the mail every few day. Set the float bowl down on it and mark the edge across the narrow dimension of the bowl. You're going to cut INSIDE these marks so the edge of the card will ultimately rest on the edges of the carb body. Scribe a line exactly 2 cm. below the edge of the card - that'll be the float height. Cut a rectangle out of the card (Xacto knife, single-edge razor blade) within the float bowl marks and along the scribed line, then hold the card up to the bottom of the carb and cut away whatever is necessary to clear the jet tower. Hold this under the carb so the bottom of the float rests on the inside edge of that 2cm box and the edge of the card contacts the bottom edge of the carb body on both sides. Turn the fuel tap on. If fuel leaks out, your float level is too high. If no fuel leaks out, lower the card just enough that it doesn't contact the edges of the carb body. If fuel doesn't start to flow out of the float valve, your float level is too low. Adjustment is made by bending the little tab that contacts the needle. Since at least some of the carbs use a needle with a spring loaded float contact, setting the float level with the carb upside down may not work. This is easier, anyway – and it doesn’t require taking the carbs off.. The motor will get along perfectly well with the level slightly low but it cannot be higher than the 2 cm level.
 

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KERRY!... The 2.0 CM you specified is NOT correct.... A CJ 360 specifys an 18.5mm float height..... Different carbs/engines are spec'd at different heights....
 

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Thanks for catching that, Steve. I knew the 360 had a different height, just thinking "450" - a momentary lapse. The card is still a good way to set the floats, though, and can be calibrated for the CJ360.
 

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I've got my carbs off my 78 CB400 because there was some significant overflow issues. I've cleaned them all up and am waiting for the parts to put them back together (float, float needle, gaskets). I'm thinking that I may need to measure and adjust my float height. I'm not quite understanding / visualizing the credit card tip.

I'm also totally new to working on bikes and rebuilding these carbs, so bear with my ignorance.

It sounds like you're cutting out a portion of the card to the specified depth which will allow you to set either side of the cut out along the edge of the carb body and check to see if the float is at that depth or not. Is this correct?

Do you have any pics you can post?
 

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These are obviously different carb models but give you an idea of the procedure..


This picture shows a similar method being used: http://www.factorypro.com/images/ca...5/Kaw_klx300,05/kaw_klx300,05IMG_0291 (5).JPG

Pay close attention to how this guy describes the underside of the carb bodies..

You can see the two points where the tool contacts the carb body. Think of that as the credit card after cutting it to allow the float to drop to the correct height. Where the two points contact the carb body you should see two flat areas on the underside of the carb body allowing the use of such a DIY tool. The rest of the underside of the body should have a raised lip of sorts that helps to center the float bowl...

http://www.salocal.com/sohc/tech/float_ ... _gauge.htm

Note the part here about the spring loaded pin in the float needle valve:
http://www.salocal.com/sohc/tech/carb/a ... flthgt.htm

I've used this method before. The long "pin" that comes out of the end of a digital/analog caliper works well for setting them too..
http://www.ktm950.info/how/carbs/Jettin ... _level.jpg


GB :mrgreen:
 

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hotel room keys work great for the gauge, they don't have any embossing and they are a little thicker than credit cards
 

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Could I trouble y'all for a little tutorial on floats / float needles / etc?

I know the basics, the gas level in the float bowl rises closing the float valve stopping the flow of gas into the carb's float bowl.

Specifically, I'm wondering at what point is the valve closed? Is it closed when the springy little tip is fully depressed? What role does that springy tip play?

I understand the basics of adjusting the float level using the credit card tip. I think I'm performing the measurement correctly. The part I am unsure of is that when I tip the carb so that the metal tang is touching, but not depressing the spring on the float needle, the float is not parallel to the carb body. Meaning closer the to tang it's (and I forget exactly) either higher (i.e. greater than 14.5 mm) than it is farther from the tang (less than 14.5 mm) or vice versa (I forget how it looks now).

Where should I be measuring the float height? I'm guessing around mid point, which if I do, the float height seems ok.

The problem I'm running in to is this. I rebuilt my carbs because there was a pretty constant overflow of gas out of the overflow tubes. I cleaned the carbs, replaced the float, float needle, all the gaskets, etc, and put it all back together. I'm still running in to the problem of gas overflowing from the overflow tubes, even with the engine running. On my last tank of gas I got about 70 miles (total, not per gallon), I'm guessing I probably lost a lot from the overflow. It also looks like maybe the previous owner tried to solve the issue by soldering the overflow tubes. They're brass in color, but there's clearly some solder along the edge of both overflows.

I have not yet tried adjusting the floats with the carbs on, as was the original post about. In my situation, this seems to make sense. I'll be able to tell if the valve is closing completely when the float is fully raised. I'm just not wild about the messiness of the process.

Thanks for helping a noob out!
BaileyMan
 

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BaileyMan said:
Could I trouble y'all for a little tutorial on floats / float needles / etc?

I know the basics, the gas level in the float bowl rises closing the float valve stopping the flow of gas into the carb's float bowl.

Specifically, I'm wondering at what point is the valve closed? Is it closed when the springy little tip is fully depressed? What role does that springy tip play?

I understand the basics of adjusting the float level using the credit card tip. I think I'm performing the measurement correctly. The part I am unsure of is that when I tip the carb so that the metal tang is touching, but not depressing the spring on the float needle, the float is not parallel to the carb body. Meaning closer the to tang it's (and I forget exactly) either higher (i.e. greater than 14.5 mm) than it is farther from the tang (less than 14.5 mm) or vice versa (I forget how it looks now).

Where should I be measuring the float height? I'm guessing around mid point, which if I do, the float height seems ok.

The problem I'm running in to is this. I rebuilt my carbs because there was a pretty constant overflow of gas out of the overflow tubes. I cleaned the carbs, replaced the float, float needle, all the gaskets, etc, and put it all back together. I'm still running in to the problem of gas overflowing from the overflow tubes, even with the engine running. On my last tank of gas I got about 70 miles (total, not per gallon), I'm guessing I probably lost a lot from the overflow. It also looks like maybe the previous owner tried to solve the issue by soldering the overflow tubes. They're brass in color, but there's clearly some solder along the edge of both overflows.

I have not yet tried adjusting the floats with the carbs on, as was the original post about. In my situation, this seems to make sense. I'll be able to tell if the valve is closing completely when the float is fully raised. I'm just not wild about the messiness of the process.

Thanks for helping a noob out!
BaileyMan
I'm not sure what model carbs you're working on (maybe CB360's?) but I'll try to answer a couple of your questions.

The float needle tip is a hard rubber material and closes the flow of gas through the float seat. The purpose of the "little springy thing" is so the float can apply pressure to the needle without putting pressure on the float tab and possible bendin/deforming the float tab. The spring applies to necessary pressure to close the needle.

Click this link to see how this individual adjusts the float on a GL1000. Granted there are 4 carbs but the technique is the same. With the carbs removed, you set the carb on it's side so that the float tang is just resting on the spring needle but is not compressing it and take your float height from that location. In my case, I just rest the carb against something solid (a vise).

When you replaced the float needle, did you replace the float seat as well? That's the brass 10mm piece that is removable that houses the needle. It's possible there might be something in there that is keeping the float needle from sealing. You can remove the seat and check it out.

If you think the float is not shutting off the fuel, I'd remove one bowl at a time and turn the fuel on while holding the float closed. Slowly lower the float and try to measure the height of the float (you are correct, the measurement is in the center of the float) when the fuel starts flowing or shuts off however you choose to measure it.

I'm posting this link since I can find it quickly but I'm sure there are more links on this forum as well.

http://www.nakedgoldwings.com/forum/vie ... c&start=30

EDIT.....I found a picture of the technique I used when setting the floats on my 450 carbs.



...and here is the page where I discuss how I set the floats on the 450.

http://www.hondatwins.net/forum/viewtopic.php?f=5&t=639&st=0&sk=t&sd=a&start=260
 

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Thanks Mike. Sorry, I forgot to mention what I'm working on...these are 78 CB400 carbs.

I didn't replace the float seat (I don't think). I didn't see anything anywhere about the seat in the Clymer's manual or on a parts diagram. I actually don't know what it looks like or where exactly it goes. It sounds like something that the rubber tip seals against when it's closed to stop the gas flow.

I did the test with carbs on the bike, and I'm able to get the gas flow to stop, and when I use the float height measuring card the flow stops.

What I did notice is that sometimes when the floats are all the way down (i.e. the needle open) it feels like it catches on something when I close it. This only happens when it is in it's most open position. If I open the needle only part way, it feels like a smooth ride to the closed position. I don't know that the force from the floats rising would be enough to overcome this little catch.

Another thing I noticed after putting the right float bowl back on was when I was checking the left side, gas was pouring out of the right side overflow, as if the valve needle was open. The bowl should have filled, and the float moved up, closing the valve.

Is this a sign of a stuck float? Is this the situation when a swift knock with a screwdriver handle to the float bowl might get it to re-seat properly?

Thanks,
BaileyMan
 

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BaileyMan said:
Thanks Mike. Sorry, I forgot to mention what I'm working on...these are 78 CB400 carbs.

I didn't replace the float seat (I don't think). I didn't see anything anywhere about the seat in the Clymer's manual or on a parts diagram. I actually don't know what it looks like or where exactly it goes. It sounds like something that the rubber tip seals against when it's closed to stop the gas flow.

I did the test with carbs on the bike, and I'm able to get the gas flow to stop, and when I use the float height measuring card the flow stops.

What I did notice is that sometimes when the floats are all the way down (i.e. the needle open) it feels like it catches on something when I close it. This only happens when it is in it's most open position. If I open the needle only part way, it feels like a smooth ride to the closed position. I don't know that the force from the floats rising would be enough to overcome this little catch.

Another thing I noticed after putting the right float bowl back on was when I was checking the left side, gas was pouring out of the right side overflow, as if the valve needle was open. The bowl should have filled, and the float moved up, closing the valve.

Is this a sign of a stuck float? Is this the situation when a swift knock with a screwdriver handle to the float bowl might get it to re-seat properly?

Thanks,
BaileyMan
I'm starting to get out of my area of comfort giving advice here since I've never opened up a CB400 carb before. My area of knowledge goes around the CB750, 450, 350 and GL1000.

However, if you put the float measuring card under the float and flow stops then it's probably set correctly. If you feel the float hanging when it's in the down position then you obviously need to investigate that further. Is the float pin nicked from pulling it out with pliers? Is the bore of the float where the pit goes damaged somehow? Is the float itself even on both side and not "racked" or twisted somehow? Did you remove the float and hold it underwater to insure integrity? Are you doing all this inspection with the carb on the bike or have you removed the carbs?

Here is a picture of my 450 carb. Right behind the float needle you can see the float seat. That is removable with a 10mm (maybe a 12mm, I don't recall) socket. I don't know if the 400 carb is the same configuration or not.



If, when the fuel is coming out of the overflow and you use the end of screwdriver to tap the bowl, if the fuel stops then clearly you've got a float hanging somehow.

Can you post a picture of the innards of the carb with the bowl removed?
 

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I found another picture that shows me removing the float seat.

 

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The carbs do seem to be different than on the ones your accustomed to. There is no removable seat like the one in your pics. The needle simply drops into the carb body.

The floats, and float needles are all brand new. I figured since I didn't know the history of the bike, I'd start fresh. I suppose there could be something inside the fuel inlet that's hanging up that needle.

All of this has been done with the carbs off the bike, except that last test where I made sure the needles were stopping the fuel flow.

I'll try tapping the float bowls next

I'll have to pull the carbs again and get some pics for you.

I'd love to be able to get to this tomorrow, but the GF and I have to do some cooking, then head over to the folks' for some grub. I'm hoping I can get back to it Friday.

Thanks for the help Mike!

Happy Holidays!

BaileyMan
 

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Another thing that made a warning buzzer sound in my head.. If the overflow tubes look like they've been soldered then they've probably split open in the past. It's common in certain models of Honda carbs. It allows the bowls to drain too early (upon filling) if they're cracked. After you've got your floats adjusted to the correct heights with the new FNV's installed then if it's still leaking it's likely to be a cracked overflow tube. The brass ones..

Just a thought.



GB :mrgreen:
 
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