Thanks I contacted mikes carburetor and am waiting a reply from their "technical" guy. The AVS has a 3 step up metering trod vs the AFB 2 step. I have a feeling a small change like this is going to mater in the carb, but will let you know what the guy says. Apparently the #489 (tall primaries) are hard to find. May see what happens with the shorties. Anybody got any tall 489 laying around?