Topic: Float Needle

[Bandit18]

Going thru my carbs again,didn't clean my tank good nuff first time.Is there a way to know if the float needle are operating the way it should.If the plunger on top is moving freely is it okay to use?...Thanks

[Bandit18]

By the way its for a 78 cb550k.

[bjbuchanan]

If the float needle isn't working correctly you will have one of two conditions:

If stuck closed from corrosion and gunk you will have a dry float bowl.

If stuck open by gunk, corrosion or stray bits from the rest of the fuel system you will have a carb that pisses gas out of the overflow tube. Really bad wear can also have a similar effect

If you see a visible ring and they are of unknown origin most likely replace. I usually like to see if stuff works as is but it is a thought

[lucky]

There are several different designs of float needles.

There is a metal float needle in a brass seat. Those were problematic because
vibration over time could make them leak by causing a step to be worn into the sealing bevel surface.
Take a magnifying glass and look at that shiny ring on the bevel tip of the float needle. See what I mean?

Those have to be replaced as a SET float needle AND seat.

The rubber tip float needles could deal with the vibration but the rubber cone tip could get degraded or deformed over time and not be concentric. Then they can leak.
The rubber tip float needle could just be replaced without replacing the seat.

The rubber tip float needle and metal tip float needle are NOT interchangeable.
They are different angles.

I have never seen a float needle with a spring and plunger that did not work.
The plunger was just there to cushion the movement.


If you have a motorcycle with a float needle with the plunger design, make sure all float needle plungers on all carbs are the same height.