40:1 should be good,most of the guys are running that(or very close),including myself.You say you're jetted correctly,but you should let us know what you have for jetting to better assist you.Is your top end in good condition....a weak set of rings/top end will cause this too.
I'm running 168 main,2nd from top on the needle,and 55 pilot....it runs quite crisp/snappy.I generally run in the midrange most of the time,and rarely wring it out wide open for any length of time.....and I get next to nothing for spooge leaking anywhere.