I wanted to correct this after almost 3 years. How timely I am!
The plastic floats WILL compress the float spring. About the only time that might not happens is with crappy float needs.
The original honda needles compressed and the aftermarket ones did to. So, turn the rack at an 45 degree angle and then measure.
And the measurement, is 14.5mm +-.5, so, in effect, 14-15mm. A mm is not that small, just use an accurate ruler.
The ride IS the adventure. The destination is just to get gas!