Float valve needle

[utbrenner]

What exactly does the little spring loaded cylinder on the end of the needle actually do?  The weight of the floats on my buddies 84 FJ1100 will NOT depress this little cylinder but on my FZ1 carbs they depress very easily.  We replaced the whole float valve assembly including new needles thinking that maybe this was a problem.  Unfortunately the weight of his floats STILL do not depress/compress this cylinder.  Is it normal?  Do some floats weigh more than others?  The o-rings were not in the best shape and the rubber looking cone shaped part of the needle had significant wear to it so i'm sure it wasn't a bad idea to replace these parts anyway I was just curious what that function of that cylinder was and/or if it's a problem that the floats still aren't depressing the needle.  Taking measurements, all of the floats were within factory spec, but i'm not sure if the measurements I took were accurate because of that cylinder not depressing.



Thanks!

[andyb]

Good question.  Mostly I think it's there just to make setting float levels a bastard.  Does that seem bitter?

Only thing I can guess at is that it acts as a cushion to prevent too much stress on the floats, and prevents vibration from allowing the needle to vibrate against the seat, causing premature wear.


Just guesses.

[utbrenner]

Good question.  Mostly I think it's there just to make setting float levels a bastard.  Does that seem bitter?

Only thing I can guess at is that it acts as a cushion to prevent too much stress on the floats, and prevents vibration from allowing the needle to vibrate against the seat, causing premature wear.


Just guesses.

Yeah that seems to be the general consensus.  I posted the same question on the FZ1OA forums.

The float pin springs for the bikes in the 80's were stiffer than the bikes 10 years later.... this is because they were trying to maximise wear from slamming the float pin into it's seat over bumps and wheelies.

Most bikes in the 70's did not have the viton tips on the float pins..... it's just evolution.