fuel leaks from carb vent hoses when on stand.

Good question, my 02 220R does the same thing.
Joe

It sounds like the float valve is worn, sticking or out of adjustment. Check out the Tech Tips section on the JustKDX web site and read through the carb float level article.

David

My '00 200 had this same problem.  I pulled the float bowl and checked the float height.  Spec is 16mm +/- 1mm.  Mine were are 15mm, which was within spec, but on the high side (allowing more fuel in).  I re-set them to 17 mm, which is within spec, but on the low side. 

I also pulled my float needle and cleaned the rubber tip.  Mine wasn't worn, but if you can see any sort of a line, or notch, on the rubber tip it's time to replace the float needle. 

I took a q-tip and scrubbed the mating surface of the brass where the float needle seats.  No particulate debris, but it pulled a lot of yellowish varnish off of there.  I think the varnish was the problem.

I've ridden the bike a couple of times since the cleaning above, and it doesn't puke gas anymore.  Hope this helps.  It's a quick fix if you have one of the above issues.

Brandon

If the float height is set to spec and it still "leaks" then the float needle is not seating correctly. Sometimes the rubber tip of the needle itself will be grooved thus not allowing it to seal properly.

If the rubber tip of the float needle looks good then you probably have some varnish build up where the tip seats with the carb body.

I just had this same exact problem a few weeks ago. I got the majorty of my information from other users on the board.

Hope this helps,
Chuck