Just getting my old '49 8N running again. It has the original six volt system and I gave it some freshening up. I've replaced the tank, fuel line, battery, plugs, points, condensor, rotor, wiring harness, ignition switch, and had the carb rebuilt by a professional shop. Fires up and runs fine at idle, but runs very rough at anything more than an idle. Compression is 90-100. I followed the instructions for adjusting main jet in carb and can't get it to smooth out. How do I determine if the rough running is spark related or carb related? Wife told me that if I don't get it fixed this weekend it should go down the road!!! Let's not have that happen!