Topic: FLOATS!

[JZEROE]

So I started up the halfé 550 yesterday after rebuilding the carbs, adjusting the valves, stripping and painting the exhaust, new shocks, new sprockets, new chain. And, after getting my jets wet, it fired right up, setlled at an 800rpm smooth idle with a quick even rev (only bench synced!).

And then I started smelling gas. There was gas dripping steadily out of all of my float bowl overflow tubes. I was SO careful when setting float bowl height, checked everything twice. I must have done something wrong, though. Here's what I did—any tips/tricks will be much appreciated:

-held carbs on their sides so that the float level adjustment tab was just touching—but not compressing—the float valve.
-adjusted to 22mm (0.866 inches). Checked both sides.

Is there a better way to hold them? Any tricks? Please help—want to RIDE this weekend.

J

[Cvillechopper]

It's happened to many of us.  Here are some of the most frequent causes that I can remember.

The floats in upside down.
The float pin is gouged from removal with pliers an not allowing the float to close.
The overflow tube is cracked.
There is still debris in the float valve.
Float valve loose in carb body/ not seated correctly.
There are monkeys in the carbs F$%king with you.

OK, so I made the last one up but the others are very common causes of this.

You could start by tapping the bowl and see if the overflow stops.

[paulages]

we just had a similar problem with a cb750- floats set properly, but still leaked on the bike. while i have found leaky overflow tubes in the past, it wasn't the case this time. i made a tool to see the actual fuel level on the bike.

i took an extra float bowl and removed the drain plug. then i pulled the fuel nipple off an old junk set of carbs and ran a 6mm X .075 thread die over the press-end of the nipple, and screwed it into where the drain plug goes. with clear fuel line on the nipple, you can let the bowl fill and see where the fuel level actually is. we keep this modified float bowl in the tool box and just swap it out on the carb to check the level. most people seem to find a big difference in bench setting vs. checking via this method. admittedly, this way would be much more of a pain in the ass on a 550 than a 750, the 550 having those hard to reach screws that hold the bowl on.

[Cvillechopper]

That does get me to thinking about a permanent mod that would allow one to see the fuel level on a 550.  Hmm..... 

[JZEROE]

Well, I KNOW the level is too high, because my carbs are pissing gas... that's my metric. 

As far as the jets and hoses being jammed up, they're not; I just rebuilt the carbs, blasted out every hole or airway with carb cleaner, and replaced every jet and hose. Those carbs are as unobstructed as a baby nursing on metamucil.

But how do you guys orient your carbs when setting the float level? I think that's where; I'm going wrong. Do you hold them sideways like I did? Upside down? Do you have any tricks to make it more accurate, or edits to the manual's spec of 22mm?

Thanks again.

J

[moham]

Well, I KNOW the level is too high, because my carbs are pissing gas...

I think the idea with checking the fuel level would be to see if the fuel was actually reaching the level of the float. If you have a cracked/leaky overflow tube, the fuel would never get to the float. Am I understanding this correctly?

[JZEROE]

I guess that makes sense, but the carbs didn't leak until I took them apart... isn't that always the way?

[Cvillechopper]

Did you replace the float valve seats?  What was done when you took them apart?  Is it every carb that's pissing gas or just 1 or 2?  Did you replace seals, washers, etc or just clean everything up?  did you remove the floats?

Moham, yeh.  That's one good reason to use the "view gas level from outside" method.  The main reason I'm interested is for tuning the carbs when the gas isn't leaking.  If the fuel isn't at the right level it makes it really hard (read almost impossible) to get tuned in correctly.

[JZEROE]

Yeah, I replaced everything.

[Cvillechopper]

Here's a test you can do to see if it's the floats or the float valve seat.  Take off a bowl on one of the offending carbs (I hope it 1 or 4).  Remove the float.  Hold the float valve in place (closed) and turn on the pet cock.  If your hand stays dry, it's float adjustment, bad floats, or a crack.  If fuel still comes out with you pushing the valve closed, there's something wrong with the valve/seat contact or the seal for teh valve seat is not working.  There was a little washer type seal for each of the valve seats, right?

There's also a chance that the floats are taking on gas.  This is not that common but would make a perfect adjustment worthless.  Might drop the float in a jar os gas and see if she floats correctly.

[JZEROE]

Each of the new float valves was a push-in style job with its own brand-new rubber o-ring around its circumference. That's what you mean by washer-type seal, right? Because that's the only seal it has. And the problem is on 3 of the 4 carbs.

[Cvillechopper]

Yeh.  Sorry, I was still thinking 750 carbs cause I worked on them last.  The rubber seal does the same thing as the flat washer on the screw-in type seats on the 750.  Basically, there are 2 ways for gas to enter the carb.  Through the valve seat or around it.  The rubber seal, if working correctly (I've mangled them on install before) forces the gas into the seat.  The valve regulates the flow of gas.  It does this by being pushed against the seat.  If there is any debris in the seat at all, you won't get a good seal and gas will get by causing an overflow. 
It is also possible that the float is not moving as it should.  Many times you'll find that the pin that holds the float in place has been chewed up by using pliers to get it out.  This can cause the float to stick open, not closing the valve.   

Did you flush the gas lines?  Is there ANY contaminate/ rust in your gas tank?  Do you have an inline filter?

[JZEROE]

Just to give you a sense of how anal-retentive I am:


Yes, those float bowls are polished. Everything is polished. All the hoses are new, and I blew them out with gasoline and compressed air before I installed them. And, like I said, I blast-cleaned every orifice in, on, and around those carbs. So it better not be debris, or I might have an OCD meltdown.

I think it's a float level problem, so here's a quick question for you all: how do you hold your carbs when you adjust the floats?

Thanks,
J

[Bob Wessner]

Just as you described.

-held carbs on their sides so that the float level adjustment tab was just touching—but not compressing—the float valve.

[jmk]

I think Cvillechopper had a good idea about taking one bowl off and holding the float up to see what happens.  Does it still leak?

[TwoTired]

I think it's a float level problem, so here's a quick question for you all: how do you hold your carbs when you adjust the floats?

If the carbs are on the bike, I'll adjust float with the carb vertical.

Other wise, on their sides, as it is easier to maintain float position and measure.

Did you lube the float seat oring during assembly?  They can get nicked/damaged and leak.  It's usually a slow leak though.

Are these both new float needles and seats?  Rubber tips or metal cones?  What brand?
The metal tips "marry" to their seats.  If you kept the old ones (that didn't leak) oriented, consider putting those back in.  I try not to replace parts like these that still work fine.

The floats can be twisted so that one is higher than the other; effects fuel level.

Other than that, check the float pivots for binding.  Did you just recently rebuild them? Or, have they sat for a while?  Did you preservative lube the internals?

Cheers,

[mystic_1]

I think Cvillechopper had a good idea about taking one bowl off and holding the float up to see what happens.  Does it still leak?

I agree - this is the test I use when I suspect a float problem.  Fortunately for me the K0 floatbowls have quick-release clips and not those annoying screws, but it would still be easier than unshipping the carb rack.

mystic_1

[JZEROE]

These are new everything—because the old stuff was, shall we say, original and proud of it—made by K&L. I didn't use preservative lube on anything. Because I don't know what it is, what I should do with it, or where I would get it.

I think the answer here is to take the carbs apart, unfortunately, and double check everything. 22mm OK, yes?

[JZEROE]

I must have been high on carb cleaner when I set these floats... they were, on average, about 4mm high. Now the #$%* runs #$%*in--no leaks.