Amal Overflow Problem:

jaydee75 · Aug 25, 2012

I went for my first extended test ride today and encountered a problem you maybe can help with:
For the past months as I restored my 75, I only kept about 2" of gas in the tank for convenience of lifting the tank off, etc. Today I rode 12 miles to a gas station. I filled it up and as I drove off it was running very rough like on one cylinder. I looked down and the left carb was pouring gas out the tickler area. I was careful to stop and pray that a fire wouldn't start. I turned off the petcock and let it dry off. What could it be? Then I guessed that for some reason the float didn't have enough force to hold the needle shut against the higher head of a full tank. Rather than try to fix it in the hot sun, I rode home using the petcock as a float level device.
Now, do you think I'm right? If the float can't shut off a full tank, what do I do? I have new stay-ups and float levels are set at .048 below the flange. The right carb did not overflow. Any suggestions?
JD75

L.A.B. · Aug 25, 2012

jaydee75 said:
Now, do you think I'm right? If the float can't shut off a full tank, what do I do?

Any suggestions?

First thing to try if fuel is dripping from the carb is to give the float bowl a sharp tap with the handle of a screwdriver or something similar, as it might be nothing more than a sticky float?

Or a speck of dirt or flake of rust could be peventing the float valve from shutting off properly?

Pattern float bowl gaskets sometimes need trimming slightly to prevent them from fouling the float arm and causing it to stick.

I suggest you remove the float bowl and check it all over carefully.

Hobot · Aug 25, 2012

LAB pretty much covered the most likely but its possible a float has leaked fuel into it or even a bowl screw slacked off but I'd had ticklers hang up float return after sitting a spell - after over a year of doing fine. Definitely look under the body to inspect the cheap metal tickler fitting which depends on a frail flair to stop em. I try to diddle float level to get best idle of 1.5 air screw turns but its more a mechanical test game to me than important as just starts idles and responds like a Commando should.

staticmoves · Aug 25, 2012

Did you install the new ticklers by chance.
If you don't line up the roll pin properly they can stick, causing some fludding.
Or if you tampered with the original tickler and roll pin it could stick a bit.
Have a look at your original float needle tip and make sure it is not worn.

Cheers.... 8)

DogT · Aug 25, 2012

You can remove the float bowls, screw them to a flat plate and run a line to them from a turkey baster or something that gives some fuel head. Use alcohol if you don't want gas all over the place. Make sure your float needle valves are seating and your float level stays where it's supposed to. Sometimes they just get old and the seat is not sharp or there's dirt or whatever in the way. Don't know if you have new needles or messed with the float bowls or how old they are or the floats are sinking. Check it out carefully, we don't want no stinkin' fires. If you need help on getting the needles to seat, we can help there too.

While you're at it, check your petcocks for leakage, just put the full tank on a shelf put a piece of paper under it and see if they leak. If they do, you'll need to fix that too.

Dave
69S

staticmoves · Aug 25, 2012

DogT said:
You can remove the float bowls, screw them to a flat plate and run a line to them from a turkey baster or something that gives some fuel head. Use alcohol if you don't want gas all over the place. Make sure your float needle valves are seating and your float level stays where it's supposed to. Sometimes they just get old and the seat is not sharp or there's dirt or whatever in the way. Don't know if you have new needles or messed with the float bowls or how old they are or the floats are sinking. Check it out carefully, we don't want no stinkin' fires. If you need help on getting the needles to seat, we can help there too.

While you're at it, check your petcocks for leakage, just put the full tank on a shelf put a piece of paper under it and see if they leak. If they do, you'll need to fix that too.

Dave

Dave looks like a lovely day in your neighborhood.
Nice hardwoods.

69S

jaydee75 · Aug 26, 2012

Let me paint the situation again. The strange thing is that I have been running the bike for short tests up and down my street for weeks. No problem. I've had the carbs apart many times to adjust, jet, and tweek. Now when I drove 12 miles to a gas station without problem, and filled up, the left carb just poured gas out. I didn't tickle, or change anything. It seems like the float needle can't hold a full tank of gas. That's what I can't figure out.
JD75

L.A.B. · Aug 26, 2012

jaydee75 said:
Let me paint the situation again. The strange thing is that I have been running the bike for short tests up and down my street for weeks. No problem. I've had the carbs apart many times to adjust, jet, and tweek. Now when I drove 12 miles to a gas station without problem, and filled up, the left carb just poured gas out. I didn't tickle, or change anything. It seems like the float needle can't hold a full tank of gas. That's what I can't figure out.

What about float needles? Are they old or new?

DogT · Aug 26, 2012

That's what I'm saying. You've got to get some head (height) on the fuel level above the float so you get good pressure against the float needle. It may hold fine with a small amount in the tank and not with a full tank. I'd take the head up a couple of feet and if it holds, you're good. It's not the quantity of head, just the height that makes the pressure.

You have new stay up floats, so they are not sinking, and I assume the new viton needles but when was the last time you looked at the needle seats. I had one that was sharp, like it should be, and another which had a taper, like someone had put a drill into it. It would not hold a seal and I managed to grind it a bit with a piece of rod and some polishing compound to seal against the viton tip. You'll probably need a strong glass to see in there and you may still not be able to see what's wrong. Unless you get it to seal, don't go there. That's why I'd give it a test with a couple feet of fuel head. It's easy enough to do and if it's not sealing, you'll need to pull the float bowl off anyhow. There's only 2 screws and the banjo. I'd check them both.

My generator was doing this when we had the derecho and I couldn't see the issue, but after several cleanings, it cleared up. The fuel was just pouring out of the air filter.

Could be something else sticking too, like the balance rod or the gasket in the way, and you can check that with the bowls off.

Yes, that pic was taken in October, all Poplar, Hickory, Oak, and some Cherry and Locust.

Dave
69S

Hobot · Aug 26, 2012

Let me paint the situation again. The strange thing is that I have been running the bike for short tests up and down my street for weeks. No problem. I've had the carbs apart many times to adjust, jet, and tweek. Now when I drove 12 miles to a gas station without problem, and filled up, the left carb just poured gas out. I didn't tickle, or change anything. It seems like the float needle can't hold a full tank of gas. That's what I can't figure out.

Jaydee let us paint the situation again, there's magic in these Nortons, too often the rest of us have to re-do something that was working fine prior and find no fault but starts working again for some unknown reason we just have to accept, or take apart again investigating and risk knocking something else unrelated to mis function, usually electrical in my cases of carb diddles. Sometimes it just fixes itself, like my Trixie which out the blue both carbs began dripping soon as gas turned on so had to lower floats but still tended to weep if taps not turned off but this last 3 wk forgot to turn off gas but was surprised no leaks at all. At least this is a place to complain too and maybe get some magic working with the mental focus of world on your mystery, which in my case has resolved things w/o any more effort on my part or doing anything different that prior, ugh.

jaydee75 · Aug 26, 2012

I've got the carbs off for inspection and maybe I found a problem. Notice in the picture that I have cut the gasket away from the axle shaft. This allows the axle to possibly move upwards the thickness of the gasket, .031. Could this be raising the needle and causing flooding?

L.A.B. · Aug 26, 2012

jaydee75 said:
I've got the carbs off for inspection and maybe I found a problem. Notice in the picture that I have cut the gasket away from the axle shaft. This allows the axle to possibly move upwards the thickness of the gasket, .031. Could this be raising the needle and causing flooding?

Yes.

Edit: That doesn't appear to be a genuine Amal float bowl gasket.

pete.v · Aug 26, 2012

Absolutely! That will cause the float to hit the base of the body before the needle can shut. When checking float height, it is nesessary to press down on the pivot point to get an accutare reading.
Why it didn't leak with little fuel in the tank is a question. Probably not quite enough pressure to unseat the float shaft.

jaydee75 said:
I've got the carbs off for inspection and maybe I found a problem. Notice in the picture that I have cut the gasket away from the axle shaft. This allows the axle to possibly move upwards the thickness of the gasket, .031. Could this be raising the needle and causing flooding?

DogT · Aug 26, 2012

I think he's got it.

jaydee75 · Aug 27, 2012

Follow UP:
I replaced the gaskets with genuine Amal gaskets that cover the axle and went for 2 rides today. No runs, no drips, no errors.
This is another illustration of how you must look after the little things.

Thanks for the comments and help.

JD75

Hobot · Aug 27, 2012

No slack cut us Commando workers. Do note that some the gaskets over ride the float too much so prevent float rise to seal off, for same signs symptoms from same components but opposite reasons, too much instead of not enough.

Amal Overflow Problem:

jaydee75

L.A.B.

Moderator

Hobot

staticmoves

DogT

staticmoves

jaydee75

L.A.B.

Moderator

DogT

Hobot

jaydee75

L.A.B.

Moderator

pete.v

DogT

jaydee75

Hobot

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