hi, i just bought a 74 sportster XLCH 1000. Rebuilt wheel to wheel, I am having trouble keeping it at an idol. It usualy turns over on the 2nd or 3rd kick but when it´s running I have to keep on the gass at about 2000 rpms to prevent it from a couple pops and a quick stall. It smells rich and back fired hear and there, usualy before it stalls. It has aftermarket drag pipes but they appear to have some black silt coming out of them and I wasn´t sure if that was normal for a bike of this age. thank you for any advice,brian baker