Purpose of float needle plunger?

[JJs80XS]

Hi! Adjusting float height on my 1980 650 and I think you're supposed to measure float height from where the float tang touches--but doesn't compress--the little plunger on the float needle. This got me thinking, what is the purpose of this plunger? The internet and all my tech manuals seem to be silent on the issue. Picture attached so that we can be sure we're talking about the same thing.

So, why have this spring loaded plunger? I got new float needles and the spring is much firmer. Is that how it should be or should the float tang easily compress it?

 

[Jan_P]

Just guessing here ..a damper ? so in case of dynamic riding --fex on rear wheel even there can be sloshing around fuel in the bowls as well as engine vibrations from the 4 stroke cycling. with no damping needle would perhaps vibrate. and wear out if i recall right it can have a rubber tip.

 

[Adamc]

Bloody good question.....

 

[Jim]

Just guessing here ..a damper ? so in case of dynamic riding --fex on rear wheel even there can be sloshing around fuel in the bowls as well as engine vibrations from the 4 stroke cycling. with no damping needle would perhaps vibrate. and wear out if i recall right it can have a rubber tip.

That would be my thought also. Without the dampening effect of the spring, the needle would be chattering against the seat from vibes, bumps etc.
Prevents premature wear of the needle and seat.

 

[JJs80XS]

I like this idea! You guys must be right--I don't know what else it could possible be for. Thank you!