Float check 1st Gen

[CrazyHorse]

I dont really care for the manual's float adjustment for 1st Gens I have the carbs off is there a way to measure the float without the tube of fuel. Can measure it when your inside the carbs?

[Squeeze]

Place the Carb in a Bowl, put a Hose on the Fuel Port of the Carb and blow Air into the Hose, fill the Bowl slowly with Fuel until the Floater Valve shuts. Measure the Level, adjust the Tab on the Floater, retest until the Level is fine. You can leave the Floater Bowl off during the Procedure.

 

Time consuming, but the only accurate Way i know.

[greg_in_london]

Don't forget - Yamaha specified different float heights for different carb specs - don't know why though, surely it's the same carb. Maybe it makes a difference, maybe not.

 

Range was about 14 ~19mm depending on model, so it's quite a difference.

[Squeeze]

16 or 17 mm might be the best shot. Everything else seems a bit too low ot too high.

[CrazyHorse]

Well I'm measured 3 times and came up with 12mm for (3) and 13mm for (1). Bike seemed to run fine. Adjust or not what do you all think? My manual says 15.5 mm to 16.5mm for a level. And which way do I adjust the tabs to get the 3mm extra fuel? Comments suggestions or am I playing with fire?

[Squeeze]

Well I'm measured 3 times and came up with 12mm for (3) and 13mm for (1). Bike seemed to run fine. Adjust or not what do you all think? My manual says 15.5 mm to 16.5mm for a level. And which way do I adjust the tabs to get the 3mm extra fuel? Comments suggestions or am I playing with fire?

 

 

Bob, how do feel your Consumption ?

 

If you feel you Mileage is good for you, just let it go. If you think there is Room for Improvement, you might do the Hassle and go through this.

 

You adjust the Floater Hight by bending the Tab on the Floater which operates the Floater Valve. Take the Floater out, insert a Slothead Screwdriver between Floater and Tab and bend it slightly to expand the Gap. Reinsert the Floater, watch out for placing the Tab between the Valve Pin and the small Wire and retest the Floater Hight.

[CrazyHorse]

I said screw it I like to tinker around so I changed the floats to what the manual says. I guess I'll see what happens. I also put in in the 42.5 pilot jets and removed the stock 37.5's like the 83 model had.

[Gearhead]

So you lowered your fuel level by 3or 4mm? That's quite a bit. Let us know if you see it in your gas mileage.

 

Jeremy

[CrazyHorse]

So you lowered your fuel level by 3or 4mm? That's quite a bit. Let us know if you see it in your gas mileage.

 

Jeremy

 

 

They are all set about to approximately 16mm + or - .5mm what a pain. I did it with carbs off bike and using a round bubble level on top of the each separate carb took forever to get it right. I'm not sure it was worth it. I was getting about 37-38mpg. But I did change the pilots to the 83 style 42.5 so I m not sure I ll see any gains in mpg. I guess I'll see.

[Gearhead]

They are all set about to approximately 16mm + or - .5mm what a pain. I did it with carbs off bike and using a round bubble level on top of the each separate carb took forever to get it right. I'm not sure it was worth it.

 

 

Yeah, that's how I end up feeling about a bunch of the stuff I do...hmm...

 

What do you mean, you used a roiund bubble level? And did you use Squeeze's bowl method?

 

Jeremy

[CrazyHorse]

No, I couldnt picture the procedure in my head I guess I'd have to see it done. I'm not sure how he would measure a 1st Gen Carb that way. Its not as nice a job as a 2nd Gen carb set appears to be in V7Gooses thread. No I took each individual carb attached a fuel line to it an filled it with fuel then placed a round bubble level on top of the carb so it was perfectly level (Simulating a level bike). I had a clear tube attached to the drain and measured the difference from the mark on the carb. Maybe I'm screwed up and am doing it wrong. If I am I sure like to know the correct way. The manual, I thought was crappy says to start bike and run it then test level. Ok thats great but if the level is off you have to take the whole carb set out and basically take it apart and guess at an adjustment put the whole carb set in again and start the bike and then measure again no way I'm doing that I'll be there for a week doing that.

Edited July 17, 2008 by CrazyHorse

[Gearhead]

Jimbob,

 

You did it right. The manuals for every bike I've had say to do it the same way, with the bike idling, which always leaves your question - what if I have to change it? The bench procedure is certainly faster, then all you have to do is take the bowl off to readjust.

 

Squeeze's way doesn't require the fuel bowl installed for measurement. If I interpret him correctly, he's saying this:

• Blow thru fuel line, perhaps with mouth. That is your indicator. When the float closes, you can't blow thru the line anymore.
  
• Set the carb with float and needle installed but no fuel bowl level in a dish big enough to hold it.
  
• Pour fuel slowly into the dish while blowing thru the fuel line. As soon as you can't blow, stop pouring.
  
• Mark the fuel level on the side of the carb where the diaphragm goes and measure the distance from there to the center of the diaphragm; there's your fuel level.
  

I've had some success in estimating the amount to bend the float tab using calipers. I measured the ratio of distances from the pivot to the center of the float body vs. the pivot to the needle tab. For example, lets say it's 1" from the float pivot to the center of the body, and .25" from the pivot to the needle tab. The ratio is 4:1. Now let's say I want to lower the fuel level by 4mm. For the fuel to change 4mm, the center of the float body must also change by about the same. Divide the 4mm by the ratio, that means I need to move the needle tab by 1mm. Figure out which way to bend the tab to lower the level, figure out a place to repeatably measure from the needle tab to the float arm, then bend until I change the distance by 1mm. Does that make sense? I've been able to get closer with fewer iterations that way.

 

Did you consider the meniscus in the measurement tube? It makes a 1mm difference depending on where on the meniscus you measure.

 

Jeremy

[CrazyHorse]

Yes I took meniscus into consideration. It was a pain I'm not really interested in doing it again I gotta say. Another thing I notice that the carbs dont all seat into the boots the same anyone else have this problem? I'm looking into seating the carbs by loosening the bracket screws to get the play to get them all to seat properly and then tighten them when they are seated.

Edited July 17, 2008 by CrazyHorse

[CrazyHorse]

Jimbob,

 

You did it right. The manuals for every bike I've had say to do it the same way, with the bike idling, which always leaves your question - what if I have to change it? The bench procedure is certainly faster, then all you have to do is take the bowl off to readjust.

 

 

Squeeze's way doesn't require the fuel bowl installed for measurement. If I interpret him correctly, he's saying this:

• Blow thru fuel line, perhaps with mouth. That is your indicator. When the float closes, you can't blow thru the line anymore.
  
• Set the carb with float and needle installed but no fuel bowl level in a dish big enough to hold it.
  
• Pour fuel slowly into the dish while blowing thru the fuel line. As soon as you can't blow, stop pouring.
  
• Mark the fuel level on the side of the carb where the diaphragm goes and measure the distance from there to the center of the diaphragm; there's your fuel level.
  

I've had some success in estimating the amount to bend the float tab using calipers. I measured the ratio of distances from the pivot to the center of the float body vs. the pivot to the needle tab. For example, lets say it's 1" from the float pivot to the center of the body, and .25" from the pivot to the needle tab. The ratio is 4:1. Now let's say I want to lower the fuel level by 4mm. For the fuel to change 4mm, the center of the float body must also change by about the same. Divide the 4mm by the ratio, that means I need to move the needle tab by 1mm. Figure out which way to bend the tab to lower the level, figure out a place to repeatably measure from the needle tab to the float arm, then bend until I change the distance by 1mm. Does that make sense? I've been able to get closer with fewer iterations that way.

 

Did you consider the meniscus in the measurement tube? It makes a 1mm difference depending on where on the meniscus you measure.

 

Jeremy

 

Hmm that does sound like a good way. Squeeze is pretty good with this stuff.

[CrazyHorse]

When I was doing this I used a micrometer to measure the tab and I was hoping to get an even reading with all four carbs lets say 3.5 mm's of tab height but it didnt work out that way.

[mbrood]

For carb alignment, one friend recommended using a large piece of paper and lay it over the lower rubber manifold and trace the holes... then compare the mounted carb rack locations.

 

With these rubber manifolds having a tendency to crack, this could be part of it. I had to use a piece of wood as a pry bar to get my carb bank up and out of the lower boots!

[CrazyHorse]

To really get the carbs to set nice in thier respectives boots for a nice seal I loosened all the carb frames bolts so the carbs could move a little. This gave me flexibiltiy to really set the carbs in thier boots nicely. I then tightened all the carb frame bolts up while they set in thier respective boots. I replaced all of the screws with stainless hex head cap screws so I could use an allen wrench to tighten them much easier then the screw heads to get them nice and tight while the carbs sat in the boots. A slow process some them dont have much room to move the bolt. This appears to give me a real nice seal around all of the the bottoms of the carbs. Something I never had before.