I'm not sure what you're reading, but you may want to recheck it. If the engine is not grounded to the frame it can cause electrical problems. The battery ground can go on the frame or the engine, but you must have good connection between the two. Most loads(device using electrical current) have only one wire going to them. The return path for the electrical current is through a common ground. Usually the frame. In your case, the return ground path for something like your headlights would be from the headlight; to the sheetmetal; to the shift linkage or clutch linkage or maybe the speedo cable to the engine and from the negative cable, finally back to the battery.
New batteries usually don't have much of a charge. If it ran before you put the new starter on then just charge the battery and prime the carb.
