bark buster

I'm in the last stages of setting up a Rotax-powered ATK for street and off-road use. The engine is an ex-flat track 500cc unit, and the frame is a '91. I'm using a 44mm Mikuni from a 600 racer, and although it idles and pulls like a train at full throttle, it's way too rich everywhere else. A smaller main helps, but I don't like leaving it too lean on top. I made up an exhaust that uses the spigots and junction from a flat-track system, with larger headers going to an FMF Q muffler.

I'm looking for someone who has a box full of used Mikuni round-slide needles, needle jets and slides. I'm getting tired of ordering new stuff that doesn't work out!

I'm in B.C., and if I could find a racer or shop that has this stuff I would be happy to pay for access to the parts and a few hours of their time.

Any suggestions?