Before you throw away that cv carb in favor of an S&S, please read this. If you haven't bored or replaced the heads on your EVO then the stock carb works great for a mildly modified bike. If all you have done is replace the stock exhaust and air filter and maybe the ignition module, then I assume by now you have felt the stock carb pop and cough at you because its too lean for the free flowing motor you have now. Just a little time and few parts you can make things right again. First I assume you HAVE a manual to tell you how to get carb off. Once its on the bench, drill a hole in the metal plug that covers the low speed adjustment. Use a metal screw and pull the plug out. Next, take off the bottom cover and remove the slow jet. If its a #42, replace with a 44 or 45. The high speed jet can be moved up to a 175 for now.If you really feel mechanical, remove the top cover and replace the slide needle with the tapered version for a 1988 sporster. Some factory carbs have this all ready depending on year. Please read manual BEFORE attempting this as it has to be put back togeather correctly. Set the slow speed at 1 1/2 to 2 turns out to get started and then re-adjust after bike has warmed up. Once you get everything dialed in right, you should have a easy starting ride that responds well to throttle and yet still gets 45-50 m.p.g. all for little money and good feeling of pride that you did it yourself. If you install a cam, you can change the bottom jets without removing carb. Hope this helps you out and if it does, please give vote. Thanks.