I'm having trouble with my mornini m1 engine. It runs really well, when it is running. But, if I let it idle too long, it will die and then I can not get it started again. It almost seems as if that spark plug is fouling out. When I remove the spark plug, it has gas/oil on it and if I clean it off, I can usually get the moped started again but it still doesnt idle well. I think my mix gas tank had a bit of extra oil settled in it (I hadnt used it in a while) when I mixed the gas last time, so it is probably a slight bit richer than 25:1. Is the high ratio of oil causing the problem? The spark plug is a nice tan color, so I'm pretty sure the mixture is right. Any ideas? Thanks.