Get a decent 2-stroke synthetic oil and mix it according to the bottle. It's the oil that determines the mix ratio (for the most part). Stihl oil that I use I mix at 50:1. At this ratio, there is very little smoke, and I never have fouled spark plugs. Also, as a 'bonus', you can use it in ALL you petrol powered machinery with no ill effects. Saves making an expensive mistake, as you only have one fuel can on site.
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