I'm not sure if this is normal or not but I have a Honda cr125 that I'm working on and when I took the pipe off there was black oil that came out the pipe and exhaust flange. Not a lot but I'd say maybe a cup or half a cup? I had only ran it for a total of 20 minutes after the rebuild. I didn't see any oil shooting out the back when it was running. I run a 32:1 oil ratio.