This is off topic, but I'll go with it anyway.

My problem with instructions for any engine is this: They assume some knowledge of engines. For those people who have NO prior experience with any kind of engine, how would they know the difference between an engine running in two-cycle and four-cycle? They should at least explain the difference between rich and lean, and what is happening when an engine is rich and lean. My professors tell us to write our papers as if the person reading it has no prior knowledge of the subject. I think that the instructions for these engines should be written the same way. My .02.