I had the same problem years ago with a near stock 400 sm blk I put a brand new 700 dp on...floor it and it would fall on it's face...EVERYONE KEPT TELLING ME BIGGER SQUIRTER YADA YADA YADA..TOO LEAN...but then I put a new 650 on it AND it came alive...the 700 had a 50 cc pump on the rear and the 650 a 30 cc pump on the secondaries...I figured it was just too much carb for what I had. (low compression small hyd cam) I have been told that 700 DP would not have come with 50 cc pump but this one did and I bought it new.