hey hope somebody can help me out.... so i am working on a friends evo big twin and he is running a keihin butterfly carb and shovelhead points.. it will start but run very shitty unless you have half choke. i finally talked him out of keeping the shitty keihin butterfly and got him a S&S super B i know it's not the best carb right now but it's better than what he's got now.. i am sure i have the points set up bang on and it is still running like a bag of shit... it is wicked lean as the pipes get hot almost instantly. if anybody can let me know anything that would be great. i'm leaning toward the carbcause the keihin air screw will not change when the screw is turned in or out... i am going to try the S&S tomorrow and see if that makes any difference.. the guy never ran any fuel filter on the bike and never did aany maintenance on it... just rode it and now it's becoming a pain in the ass trying to get it back to running condition... thanks for reading!!