Improper float setting cause case flooding?

If I have my floats set wrong---will it cause the bowl on the carbs to overfill and fill the engine with fuel???? I am at an end with these carbs. I have replaced the needle valve sets with new. I soaked the floats for 3 days and they floated all the time. I've replaced about every part inside my carbs with new but still the carbs fill the engine with fuel after a couple of days of sitting.

I put my bike on a 2x4 piece of wood with the center stand. I then added a bunch of wood under the front tire to make the carbs as level as possible. Then using clear plastic tubing inside the drains of the bowls, I check the float level. But for the 4th time, it still overfills the carbs.

My petcock must still be leaking through. I have not found a used one yet.

please give me some advice of what to do.

dave

 

Buy a NEW Petcock.
Get a Hot-Rod Guy who knows how to measure the heights.
Put a Briggs & Stratton Fuel Shut-Off Valve on it.
The Carbs don't need to be on the Bike to do Float Heights.
On the Bench ... using Windshield Washer Fluid ... will speed the process.
You can't light washer fluid and it don't stink-up the shop.

You can Measure the TANG BEND if you have a Mechanics Precision Ruler.
Mechanics Precision Ruler ... with Pocket Clip & "T"

6-Inch Square of Plexiglas -- (Or a pane of glass which you will break.)
Fill the Bowls.
Pick one that's right.

Drain the Washer Fluid in a Bucket or right on to the shop floor and use a towel to absorb the Fluid which cleans the floor if it needs it.

Pull the Bowls.
Pull the Floats.
Take the "Winner" and lay it on the edge of the glass so the Tang points UP.
Measure the Height from the Glass to the Top of the Tang.
Use the Sliding T on the Ruler.
Read the Scale on the "One-Hundredths" side.
Double check.
Now, armed with the right measurement ... match-Up the other three!

This beats going through a few gallons of Washer Fluid and bending the Tangs up and down so much that they finally get brittle enough and fall off.
Give it a shot.
You might nail it on the first try.

 

Im on the hunt for a used petcock---I replaced mine with a new one from Yamaha and have had nothing but problems. My original one is not usuable.

I will try the float level setting on the bench as suggested. thanks

 

You might bring your fuel cock back to the Yamaha dealer and exchange it for another new one. I would bring your carb rack along with the correct page from your service manual to someone who know how to set the float levels.

Let us know how it goes.

 

Re; bench-setting float levels: Don't use windshield washer fluid, it has a different specific gravity than gasoline and you'll end up with incorrect levels. I had been advocating WW fluid for safety reasons until another member discovered that it doesn't give accurate results.

Once your floats are set/checked, you should be able to LEAVE the rig for a day or two, supplied with gas, OVER A CATCH BASIN OF SOME SORT, to see if the float needles really are doing their job.

Once the carbs are "shutting off" reliably, then address the petcock.

I know you said you replaced your needle valves and seats with "new" so you probabaly don't want to hear this, but...
There are some real garbage carb parts on the aftermarket; if you used poorly engineered or inferior parts they very well may NOT work correctly even when new. You're going to have to "static test" until you determine the cause.

 

The Specific Gravity of Regular Gasoline is: 737.22 (With additives added), the Specific Gravity of Isopropyl Alcohol is: 785.40, ... Ethyl Alcohol comes in at just around: 789.20

Gas = 737 ... Lets call it 740 ... Ethyl = 789 ... we'll say 790

The Float Height in the Factory Manual shows the meniscus of the Fluid in the Measuring Hose to be LEVEL with the Top of the Lock Washer above the Screw fastening the Fuel Bowl to the Carb Body.

The Tolerance allowed is: + / - 1mm

 

OK. So I will use gas to set carb height or Ethyl---It doesnt matter to me, I work in smelly stuff on a regular basis.

As for replacing the petcock, I've looked and looked and posted and looked for a used one. The new one I have is over a year old that I bought from a company on the net (it had yamaha packaging). I would love to find another petcock.

I have to take the carbs back off again and then make some kind of leveling bench with a contraption to feed fuel to the carbs once its ready, so give me some time----my motivation is real low right now. And yes, the engine oil case is full of gas.

 

I don't understand, why would specific gravity matter?

 

Because somebody told Fitz that using Washer Fluid instead of Gasoline caused there to be an inaccurate measurement of the actual Float Height.
I doubt that that is true. Both Fluids are "7-Something"

Scientifically, there would be a difference. ---> = .000225 mm
But the difference is closer to NONE than it is to 1.

Using Washer Fluid ... you can be "Green":
Be working setting Float Heights at the Kitchen Table enjoying a nice Cigar and letting the Carbs drain out into the sink.

Using Gas is Dangerous.

 

Ok, so i took the carbs apart and adjusted the floats. Then I made a wood block set to level the carbs and also made the supply for fuel on my work bench. It leaked the first time, so i put some sealer around the fitting in the coffee can. Hopefully my pics will work.

I will check floats tomorrow when the sealer is cured. As for the bike and the leaking petcock, I put a Mt. Dew can to catch fuel leaking out of the petcock----day 3 and not a drop!! What the heck? When the carbs are on, it overfills the engine case with fuel. I guess its a syphon of fuel with the carbs hooked up. With the open end of the fuel line---nothing drips or leaks. Crazy!!!!

dave


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