you MUST adjust the needle for your setup. I had a ton of problems with mine trying to get it tuned and now its pretty much perfect.
airsal, homoet, 20mm mikuni yielded me a 165 main jet with the needle second from the top setting. PLENTY of people have seen mine rip at the rallies. Its all about getting your main jet close, and then adjusting the needle... at least thats what worked for me.