Float Height

[Threkin]

 Hello everybody =)

I am having an issue with gas leaking (yea, really!) out of the overflow tubes almost always after taking a long ride, and only after it's been parked for a while, it almost never happens when the engine is running.

I have to assume the float height is bad on the offending carb, letting unmetered fuel in the engine while its running, (I'll take a look at the plugs here in a minute)  and overflowing when its off. Do the doctors concur?

What I need help with is exactly how to use the clear tube and drain screw method. I have searched my arse off and I can't find a specific height the fuel to be on the carb. The manual says use the fuel tool to set it 2mm above the bowl, and the illustration is clear as mud.

Thanks in advance for anyone willing to help me out!

[Threkin]

 Heres a pic to show what I'm looking at:

Seems like the level is really really low? Should it be even with #1 or #2?


No one ever accused me of being an artist =)

[andyb]

Float height isn't the problem.  Fuel level is the problem.  Reason it's a problem is that the float needles aren't able to stop fuel from coming into the bowl.

Take the carbs off, pull the needle seats out, stick new o-rings on them, and put it back together.  95% chance that is all you'll need to get it sorted.  While you have the float needles out, inspect their tips, if they're worn significantly you'll do best to replace those also.

[Threkin]

Float height isn't the problem.  Fuel level is the problem.  Reason it's a problem is that the float needles aren't able to stop fuel from coming into the bowl.

Take the carbs off, pull the needle seats out, stick new o-rings on them, and put it back together.  95% chance that is all you'll need to get it sorted.  While you have the float needles out, inspect their tips, if they're worn significantly you'll do best to replace those also.

Thanks Andy, the first thing I did last time I had em apart was change the seat o-rings.  I ordered the 1mm larger ones from McMaster Carr that oldslowguy recommended. It still leaks out of the overflow after every ride.

Isin't float height directly proportional to fuel level?

[andyb]

It is, absolutely, unless it's leaking past the needles or seats.

If they're newish and not leaking at that point, then yes, you definitely have a problem that you should be able to adjust I'd think.

[Threkin]

Thanks again Andy.

Now I'm beggining to suspect a bad float, after looking at the fuel levels of all four carbs, they are all pretty close to whats in the above pic.
It seems likes thats pretty low, too low to cause an overflow situation.

Why would it take 30 minutes after I shut it off to start leaking? What would cause that? Seems to me a slowly sinking float would do that, but why would the float only sink when it's parked? Makes no sense...

I get the feeling I'm barking up the wrong tree.

[racerrad8]

It is going to be from heat causing the fuel to percolate or expand. Which overflow hose(s) is it coming from? the large (2) or small (4).

There is fuel stored in a restricted well withing the bowl for the choke circuit which is the small tube that act as the vent to draw that fuel when needed for the choke function.

The two large hoses are hooked to the white tee between the two carb bodies. That is the actual float bowl vent/overflow.

You could easily hook four clear hoses up and see if one or more carb raises the fuel level and it would be obvious on the fuel level in the hose.

You might be back to the installation of a petcock if the fuel level is raising and the float circuit checked out properly.

Keep us posted,

Randy - RPM

[Threkin]

 Thanks for the help Randy!

Its coming from the smaller hoses, not the big ones. Wow, I think I have heard that said before but it didn't register. Big ones are actuall overflow, small ones are choke circuit vents. Thanks for getting me straight on that.

Please clarify what I should do with the clear hoses, I think you mean right when I'm done riding put a hose on each carb and open the drain to see what happens?


*Ahh*  and I see your reply to my other post which answers this one perfectly, 2mm below the bowl mounting flange if someone else is wondering about fuel height. Thanks again Randy.

[racerrad8]

Please clarify what I should do with the clear hoses, I think you mean right when I'm done riding put a hose on each carb and open the drain to see what happens?

Exactly, just to make sure it is not a float that is sinking and causing the overflow.

And the actual setting of the fuel/float height is 3.0 mm +/- 1mm.

Good luck,
            Randy - RPM

[Threkin]

  Well as it turns out I think it was just some crap stuck under the float valve.

I was checking float height with a clear tube and a pretty fair amount of brown/red debris came out of the offending carb. I let the gas flow until there was no more crap.

I was feeling too lazy to take the carbs off again so I started it up for a couple minutes, which would usually induce the gas drainage, and shut er off and went to bed. Next day I went for a spirited ride up the canyons for a couple hours, then parked it and nothing. Bone dry.

Sounds to me like the root of the issue is some cancer in the gas tank. Maybe I should let my urologist have a go at it. Or maybe I need to start thinking about some Kreem, some steam or a fuel filter.

The tank wasn't too bad, I did a pretty outstanding job of getting most (I thought I got em all, guess not)  of the rusty spots off with a scotchbrite on a coat hanger and a mirror.

My gas level was in between 1/2 inch and 3/4, alot lower than 2mm but the bike runs great so I ain't gonna fiddle with it.

[Yamifj1200]

for the love of god DO NOT use creme gas tank sealer in your gas tank. JMO

Eric M

[the fan]

Visit the hardware store and pick up a 2 gallons of CLR and a handful of steel nuts. (I used a similar product by ZEP).

Remove tank and drain.

remove the petcock and plug the hole.

Pour in 1 gallon of CLR along with the nuts.

Shake the tank for about 1 minute  and then let soak. Repeat every so ofter over the next few hours depending on how much rust is present.

Remove steel nuts with magnet and top off with 2nd gallon of CLR and water.

let sit overnight and then drain into 5 gallon bucket. The diluted CLR is great for cleaning jobs around the garage, but will stain concrete...

Once clr is removed mix 4 ozs 2 stroke oil with 1 qt of gas. Pour into tank and swirl around until everything is coated. This should disburse the remaining water and protect the tank from rust.

Drain 2 stroke mix and reinstall tank.

I have done several tanks this way with good results. so far none have rusted again. For a more permanant fix replace the CLT with Muratic acid (used commonly to clean masonry) or Phosphoric acid (Paint stores, used to prep metal) but be very careful as these will burn skin and can easily damage paint.

[UJM]

for the love of god DO NOT use creme gas tank sealer in your gas tank. JMO

Eric M

I've had good luck with Kreem tank sealer, but it is not as easy as many believe to apply properly.

Have to properly prep the tank and follow the instructions to a tee - I've seen far too many half-hearted attempts that caused a lot of problems, it is not for everyone, that is for sure!

KREEM FUEL TANK LINER is designed for use as a preventive maintenance product in metal tanks new and old; containing gasoline, gasohol, or diesel. KREEM TANK LINER has a unique formulation with extremely rapid set-up that prevents leakage from hairline cracks and seam pinholes by coating the tank's inner surface with a fuel resistant elastomer. Not for plastic tanks. KREEM is NOT compatible with all fiberglass tanks. You must spot test before use. Read the Kreem "how to" brochure for detailed application instructions.

http://www.kreemproducts.net/default.aspx

[Threkin]

 Thanks for the advice guys,

Thought I'd give a update and let everyone know my FJ is running excellent.

I believe the issue was just some crap got under the float needle, no big deal.

I really do need to get a petcock on it so I can leave the tank full in the winter so I don't have to worry about RTS (rusty tank syndrome), and Randy you will be the first person I talk to about that.

I gave up on worrying about float height, when I checked it with the clear tube it looked extremely low in each carb, exactly the opposite I expected it to be. So I just left that alone. No need to fix something that ain't broke, I always say.

Anywho I would call this mystery solved, and I woulden't have gotten away with it if it weren't for you meddling kids!

*Edit* It just dawned on me a few years ago I bought a used set of carbs that were on a later bike, one with a fuel pump I believe. What jogged my memory was that the float valve seat was different than the ones on my old set of carbs. I mangled one of the screens and tried to change it out with one from my old carbs, and it wasen't the same. So I am fairly sure I'm running fuel pump carbs on a non fuel pump bike. Whats your thoughts about that?

[racerman_27410]

well all right......

  the KISS method of troubleshooting wins again !


Kookaloo!