Fuel Petcock problem

there is a round, neoprene disk in there with 3 or 4 holes - also there is a thin spring that looks like a washer that presses everything together

very simple

take your old one to a honda shop & they will probably have a neoprene disk that will work

haven't seen one exactly like that before - looks like the fastener on that shaft should slide all the way down to the circlip & thread into the body of the petcock

on the end of that shaft, the circlip *should* be pushing a metal disk that will allow fuel to flow thru one of the holes, or neither depending on which way the handle is pointing - usually, there is also a springy washer that sits between the metal disk & the threaded part on the shaft

EDIT: a quick search shows these may be hard to find - you might consider putting a cheap after market petcock on

You are missing the piece that fits onto the end of the control shaft. This is why there is now alot of in and out play of the shaft.
I have seen them made of white plastic as well as pot metal.
It will be round and the same size as the 3 holed rubber washer.
On the back side it will have a "C" shaped channel on the face of it that contacts the rubber 3 hole washer.
On the front side it will have a hole with a raised bar going from one side to the other that the slot on the end of the control shaft locates into.
You are also missing a cone shaped spring (sometimes they are a wavy spring instead) that presses the missing piece snugly against the rubber 3 hole washer.

Treatland may sell an entire fuel valve if you just want to replace it instead of repairing it. You gotta hunt for it yourself though.
Look here: http://www.treatland.tv/
Click on the tiny treatland.tv button on the home page.
Go to the "find by parts" window and click on the down arrow on the right side of it.
Click on the petcock section.

Happy hunting!