Harley 9B carb help needed.

[Ian Biddle]

After years of problem free operation my 1913 9B has started to spray or 'pulse' fuel from the bottom of the float bowl (main nozzle). After inspection I replaced the float which was cork and had deteriorated and then re-assembled it but the problem remains. I have checked the carb settings, all the usual stuff. I'm sure the problem must be the carb but the pulse relates to the stroke so I also rechecked the inlet timing. No leaks, easy starting and the motor runs great but the spray is a problem. The only recent alteration has been installing a new throttle shaft. Can anyone point me in the right direction please.
Thanks.

[T. Cotten]

What kind of replacement float did you install, Ian?

There's some HX boat anchors out there, both brass and molded.

The next thing I would inspect would naturally be the airvalve.

....Cotten

[Ian Biddle]

I used a moulded Nitrofill (Nitrile) type. They seem good and are what I have used on my other teensters.
The Schebler manual also suggests the air valve. The stem might be loose in the adjuster but I wondered if I am missing anything more obvious before I tackle the valve.
Thanks for your advice.

[T. Cotten]

Did you weigh your new float, Ian?

Or at least compare them, hand to hand?

(And beware of swelling in USA fuels...)

....Cotten
PS: There's been at least thirteen different Nitrophyls, not counting the counterfeits.
Only the very last has proven itself against P4gas, and nobody (except auto manufacturers) paid the royalty to mold it.

[Ian Biddle]

Hi Cotten, no I did not weigh the two floats but the old cork and the new Nitrile floats are similar in size.
There is plenty of clearance in the bowl, no binding and good movement when fuel rises.
The new float has only been in a few days so no swelling yet! I presumed Nitrile would not swell.
I was not aware this was such an issue.
Is your suggestion that the density of the float might mean there is still too much flow of fuel?
Thanks.

[T. Cotten]

Please consider, Ian,...

If the same size of float weighs three times as much.

T'aint nothing "nitrile", no matter what you bought... (Since the proprietor of the original Nitrophyl won't protect their name, its become "generic".)

Stay away from P4gas, or it won't stay the same size either.

....Cotten

[Ian Biddle]

Thanks again, I'll get the weighing scales out tomorrow.

[Ian Biddle]

The old cork float was 2.5 grams and the Nitrile was 5 grams. The depth of the latter was also much deeper (18mm v 12.5mm). I turned the Nitrile one down in size removing 2 grams.
After refitting I still had the same problem. Now I will look at the air valve.

[T. Cotten]

Buoyancy, Ian,..

Isn't just about weight, but also volume.

Making the float lighter doesn't help if it makes it smaller.

A buoyant float can be set to book spec, saving a lot of tail-chasing.

....Cotten
PS: Please note in this jar of fuel are four different 'nitrophyl' Linkert replacements, including the one on the bottom
Making it smaller won't make it float.

[Steve Swan]

Ian, buy one of Tom's Durable lifetime guarantee floats and the float variable will be removed from the equation.

[T. Cotten]

Thanks Steve!

Lifetime as long as I'm alive.

But what's my guarantee if the material goes extinct?

(Where's my trolls when I need them for a punchline...)

....Cotten
PS: I finally found my pic of a molded H float. Miy production is appears porous, because it is machined from pre-cast boards.

[Ian Biddle]

Where do I get one of these floats?

[Ian Biddle]

and are the float lever, valve, etc also available?
It might make sense to change all the parts if possible.
Thanks again Tom & Steve.

[T. Cotten]

You can always email me direct at liberty@npoint.net, Ian!

I don't change out floatlevers, I die-press the pin bores tight on a 3/32" drill shank, and then ream out to fit the fresh pin.
This slightly widens it, allowing to be centered by filing only one side.

But the floatvalve needle itself is certainly best replaced, along with re-cutting and burnishing the seat of course.
(Unfortunately, my commissioned inventory of Monel-tipped needles are reserved for my services, and I have no experience with ebay brass and stainless offerings.)

Especially with this early stuff, oftener its better to fix what you have than buy a funky reproduction.

Happy to help if I can,

....Cotten
PS: Oftener is a harley word, like on their aircleaners.

[Steve Swan]

Where do I get one of these floats?

from Tom Cotten