Topic: float needle valve

[lash]

What is the difference between 2.0 and 2.5 float needle valves? Which years used which version? How does this affect performance?

[kerryb]

First off, I'm making this up, but here's what I found.  2.0mm valves are for cb750k 69-75, however, the cmsnl photo for a 76 carb also shows a 2.0 needle seat.  2.5mm only shows a needle available, and the cb750's are much later years ( late 80's -early 90's)  biggest visible difference is the rubber tip on the later ones
Simple answer...bigger needle valves flow more fuel.
There's a start.