Premix Ratio?

[HotTrak]

I am trying to figure out the optimal premix ratio for my 1982 KDX250. The original service manual I just got says 20:1, but a coworker I ride with suggested that I could run a leaner oil mixture with a synthetic oil. When I went out with him a few weeks ago, I used some of his 40:1, and the bike seemed to perform well. I'm new to 2-strokes, so this is all greek to me so far.

[scheckaet]

check sig for newb how to and jetting / ratio mix.

[KDXGarage]

Back then, oil was not as good as now, so it may have needed more oil of that type than a modern oil. A couple of the older manuals are that way. With a modern oil, I would suggest 32:1 to 40:1 for your application, depending upon how hard the engine is working.