Topic: Need help, please

[traveler]

Need help, please,

My #1 carb leaks.  I have taken the bowl off, and turned the fuel on, and then pushed up on the float and the fuel stops, so the seal between the float needle and seat are ok.  I have the float adjusted so that the float shuts off at the same level as the pilot jet....the minimum level.  Still leaks.  I have "floated" the float in water to see it it still floats or not...it is good.  When installed, it has free play.  The carbs works, yet it still leaks.  I have seen wetness around the pilot jet opening on the throat of the carb and can swear I have seen it "burp" out of the jet hole, and it also has come out of the upper overflow hole in the housing  I have the bowls drain screws turned all the way in....when I open them just a tad to let the overflow work, fuel RUSHES out the overlow tube, so the float isn't shutting off the fuel, but I have set the float already.  The bikes runs good, but it's either let the fuel dribble down the sprocket cover forever, or fashion a 1 inch band of cloth around the bowl and zip tie it on, and let the cloth dry out in the air as I am riding and forget it.

In short....I am at wits end, and am feeling resigned to just letting it leak, but would like to know if anyone on here has any ideas.

HELP! (please)

~Joe

[Retro Rocket]

Hi Joe, i am no carb guru by a long shot but you are correct, it shouldn't leak. Did you try lowering the float a touch so it shuts fuel delivery a little bit earlier...?

Mick

[traveler]

Yeah....that's what I did... I lowered it until it was right at the point where the pilot jet would need fuel....any lower and that jet would starve.

~Joe

[scottly]

Try swapping the float needle from that carb with one that is working properly; say, from 1 to 4.

[754]

 I am sort of thinking, there is a crack, or chipped piece.

 The inlet seat screws into  the body, and should have a fiber or soft metal washer.. check that. If there is a crack, it can leak.
 If you drop the bowl, hold the float up in closed position, turn gas on a few seconds, you may be able to see where it leaks.

 Do this OUTSIDE  , helper dont hurt either, or a fire extinguisher..

[TwoTired]

Check the stand pipe in the leaking bowl for hairline cracks.

[Jerry Rxman Griffin aka MuthaF'er]

Overflow tube have a hairline crack?

[BeSeeingYou]

My guess is that the needle valve and seat are still suspect.  While it may not leak when you hold the float up you may be putting more pressure on it than the float would be capable of doing and that may stop it from leaking.  Just a thought.

[traveler]

Okay....I am suspecting the same.  Yes, when I hold the float up GENTLY until the fuel flow stops, it turns off right at the point where the pilot jet can get it's fuel, so the fuel level is correct.

Does anyone have a PD46a carb body they can live without?  If so, I guess, I'll have to swap it out.

can also try the swapping float needle idea.

Thanks.

~Joe

[mrrch]

We use a little pressure tester to check needle & seats. You invert the carb pump it up and it should hold approx 5 psi before opening.  Useful litte tool, alot of new needle & seats fail surprisingly. Motion Pro has them.

[mycb750k6]

I thought you were not supposed to mix float valve pairs as they tend to wear together just like you shouldn't switch around idle screws. Otherwise you could end up with them all leaking. What kind of floats do you have, the brass or plastic kind? I had a leaking brass float but you couldn't tell unless you shook it to hear the gas slosh around.

[Jerry Rxman Griffin aka MuthaF'er]

Joe,

I don't know your carbs. I'm thinking from the standpoint of early 750 carbs.

Is the float pivoting on the pin properly and not snagging? Remove the pin and take some very fine sandpaper like crocus cloth and polish the pin. Be sure that area of the float is not pinched too tightly.

Where is it actually leaking from? I didn't see that mentioned. I'm assuming it's not the bowl gasket. Coming from the throat of the carb? The overflow? First thing I'd suspect is leaking past the float needle. It shuts off with hand pressure but perhaps not with float pressure? The floats float but does one have a leak? If it fills up with fuel then it won't float as well and you might expect a rich condition since it would sit lower in the bowl allowing more fuel flow. And if this is the case then you may not get enough upward pressure to close the needle onto the seat. Is the needle being pushed upward with enough perpendicular force to create the seal? ie something bent/not aligned well enough to create the seal. Did you set the float height with a gauge for known accuracy? Is one of the float pin posts slightly bent causing a misalignment?

One of the guys mentioned swapping carb pieces from a non-leaker. I think that is a good idea however I'd first use a gauge to insure correct float height. Only make one change at a time so you'll know what single culprit you have. I'd be sure to do a swap into both carbs and button both back up! Hopefully the problem will transfer to the donor carb. Swap a float. If that doesn't work put the original float back in and swap out a good needle and seat SET. If this doesn't work the only other thing I could think of would be the cracked overflow tube situation.

I've tried aftermarket carb kits only 1 time. Used Keyster and I was worse off than before I started. If you find it is the float needle/seat get a new set from Honda if available. You may also be able to find aftermarket rubber tipped needles to use.

If none of this works and no one else has a solution the carb body may be your best bet.















   

[Flying J]

I may have a carb body but i think jerry hit. I had issued with my PD carbs over flowing. Hold the overflow tube up next to the carb with the end above the carb throat. If gas starts pouring out the throat then you needle is leaking. If  Not then it is the overflow tube. I have had issues with both. For the leaky tube, i replaced the bowl. For the leaky needle i used some fine aluminum polish on a q-tip and polished the needle seat a little and the cleaned it real good. that fixed it. Or i guess you could do that and buy a new needle. I would try all that before i pulled off and replaced the body. But if that doesnt work PM me and ill dig through my box and see if i have a #1 carb body.

Jason

[flybox1]

Yes, when I hold the float up GENTLY until the fuel flow stops, it turns off right at the point where the pilot jet can get it's fuel, so the fuel level is correct.

How have you verified this?

did you use the "clear tubing out the drain screw hole" method?

if your bowl is still leaking, either out the overflow, or from the gasket seam, your float is not closing the fuel valve completely.  is suspect the fuel level in the clear tube will confirm this if you try it.....any level in the tube higher than 4mm below the gasket seam line, and your floats need to be readjusted to close the valve earlier.

[Flying J]

like this. disregard the numbers

[cameron]

Hmm..

Does it leak when the engine is OFF, or when it is running, or both?

[traveler]

When does it leak?  whenever the spigot is turned "ON"

With the bowl off, I turned on the fuel, and fuel started running out.  I gently pushed up on the float until it stopped.  It stopped right where the pilot jet is.  Any lower than that, and the jet will not get any fuel.....In other words, it can't go any lower.

I know the float bowl gasket is good because when you take the carbs off, fuel dosen't leak out of the bowl until you remove the screws and pull the bowl off, then the remining fuel runs out.

On the float....I floated it in water, the float is good.  It freely moves on the shaft as well.

I have inspected the needle, and the tip is nice and clean, with a sharp point, just like God and Soichiro Honda intended.  The seat has also been wiped clean with a Q-tip.

Still....carb leaks.  With a good float, clean surfaces, and the needle valve shutting the fuel level off....it must be a crack in the housing.  The carb is working, just leaks, and burns a tad richer than the others.  

If you have a #1 carb body, I'd be more than willing to buy it from you.

Thanks,

~Joe
 

[cameron]

Oh good! Leaking when the engine is off is much easier.

So, I tried to find it in our previous, but I am still unclear... but lets work through this:

In a normal system, with the bike on center, if you have good floats, the fuel will never get out of he BOWL, correct?
It wont hit the overflow, so if it is leaking under these conditions it can only be 2 places:

1. Your drain screw
2. your INLET.

Right? Maybe I am missing a spot?

Of course, that it assuming the float/valve situation is correct.
Even with a totally ruined top part, you shouldn't see a leak while the engine is OFF if your floats are good... Except from those 2 spots, no?

Check my logic.

[Flying J]

Where exactly is it leaking from? Is it coming out the over flow tube or out the carb itself. I will go look in my box.

[zzpete]

Check the carb FAQ page 1 about half way down entitled:Carbs still dripping? Could be a cracked tube!
http://forums.sohc4.net/index.php?topic=5410.msg245572#msg245572

[justind511]

the overflow tube inside the bowl could have a crack. you can put a clear rubber hose over it and see if it helps. i read that in another post somewhere on here

[traveler]

A crack in the tube won't matter much, as it is leaking out of the breather vent holes above the float bowl......the fuel level is rising ABOVE the float!


I have the drain screw turned ALL the way in......when I opened it, fuel POURED out the overflow tube on the bottom of the float bowl cover.

It leaks BOTH when riding and when off.

~Joe

[cameron]

If it is above the bowls, it HAS to be the float system. right?
But that doesn't jive with your clear-tube measure, does it? Hmm.

OR< MAYBE, an inlet problem, and the gas is sneaking around and just pretending to come from somewhere else?
I think this, since nothing else really makes sense! You cant have a working float/needle, and still spill gas from above the floats. . . not without my brain exploding!

Can you dry them off, dust them with powder and then open it up.. REALLY get to the bottom of where the leak is?

[traveler]

here is the thing.....with the float bowl off, and the fuel turn on....when I GENTLY push up on the float, the fuel stops, and when you sit and wait for leaks, there are none.

Basically.....the float is good, the float needle seals, but for some reason, the fuel jsut rises past the float.

That's why I'm ready to just replace that carb.

~Joe

[justind511]

this might sound crazy but one of my carbs ould leak out the overflow after cleanging them. if i pushed up on the float it would shut off, so i cleaned the needle and put back together and still leaked. what i did to fix it was lightly rub the needle against emory cloth. i fugured if i messed it up more i would buy another carb kit. but it worked no more leaks! been about 2 weeks now

[traveler]

but the tip of my needle is rubber!

~Joe

[cameron]

OK..

So it DOESn'T leak when you manually move the float.

It DOES leak when the bowls are ON,..

It must be the float.

Maybe the float is rubbing against the BOWL? So it is frozen with the bowl on?

[traveler]

when I had the bowl off yesterday, and then put it back on....I moved the carb back and forth, and could hear the float moving in there.

~Joe

[cameron]

Hmm.
Well, lets postulate that the Float is floating.

THEN, the only thing that can possibly be preventing gas shut-off is the valve, right?
If the float is good, the valve must be either bad or sitting wrong.
Have you tried switching that valve to a different carb? (maybe the float, too, just in case?) That seems like a good idea.

Luckily, I heard that if your carb leaks enough gas into your engine, the whole thing can actually explode while you are riding.

[traveler]

It's not leaking THAT much fuel....it is running a tad bit richer than the other cylinders.



~Joe

[Kframe]

Just tossing this out there (don't even know if this would cause the problem) but... is the float being installed upside-down? 

-K

[droopy]

had a float that was slightly twisted on one side would move fine butt with fuel would catch on float bowl  look at float several times before i saw it

[traveler]

i'll check it again...thanks.

[flybox1]

I still think its a faulty float valve....or the spring inside it.
yeah your float is good, but the pressure it imparts on the valve is much less than your finger.

i'd say you have an original float valve with a worn out spring, or you rebuilt your carbs and the new valve is not seating properly with the pressure your float applies as the gas rises...

am i way off base?

[Flying J]

I still think its a faulty float valve....or the spring inside it.
yeah your float is good, but the pressure it imparts on the valve is much less than your finger.

i'd say you have an original float valve with a worn out spring, or you rebuilt your carbs and the new valve is not seating properly with the pressure your float applies as the gas rises...

am i way off base?

Im with ya on that one. I would change the needles around and see if the problem stayed or moved.