Anyone know how to best tweak a PC-III map?

[any4xx]

For elevation or to change the base A/F ratio?

I had a friend tune my PC-III USB on his dyno at sea level. He set the entire range at 13.8. I live at almost 6,000' elevation and I'd like to lean it out just a bit more. The cell numbers on the fuel map are all over the board, but I was looking over his shoulder as he tuned so I know that the A/F ratio is constant throughout the range. Would I want to reduce ALL numbers by a percentage, or just by a set amount? In other words, if four cells have 20, 40, 60, and 80, would I want to reduce them all by the same amount and change them to 15, 35, 55, and 75, or reduce them all by the same percentage and change them to 15, 30, 45, and 60 to maintain the same levels of change?

Also, does anyone know just what A/F ratio I can expect at a given elevation if I know the A/F ratio at sea level?

Thanks,
Tom.

[barrybasinger]

I often have my bike dynoed by a friend at Daytona, and I live at a little over a thousand feet. I generally go around 2% leaner when I get home.

When I plan to ride through the West, I just use the buttons rather than hooking up the laptop. You might want to try the same thing until you find the setting that works well for you.

I think that 1% per thou is plenty conservative enough to get you in the ballpark without danger of going too lean. If I were you, I'd start by leaning everything 6-10% and see how it reacts. Plugs should clean up some, mileage should get a lot better, etc. You might have to leave the 1000 RPM/0% settings as they were, but probably not.

If your mostly-level highway mileage at 60-65MPH isn't up around 43-45 mpg or better, you're probably still too rich at 40% or so and 2250 RPM or so.

P.S. I'da never let him set it at 13.8 everywhere. Using on-road data logging, I set mine at very high 14's at all cruise settings, and low-to-mid-13s at 80% and above. (And no, I don't care what Donnie says--no disrespect intended).