Hey Capt. Bob,
You are correct, "wean off of leaded gas" was what I meant to say. Specifically, depending on the carburator design, jets will either meter air or gasoline. "Fuel" is actually the mixture of the two. Most outboard jet designs meter gasoline. In the case of our 1975 85 Evinrude; it happened to be the year that lead was removed from gasoline. Lead was an octane booster among other things. So when the lead was removed the octane calculation method changed and the fuel became "under octaned" The only fuel that was still usable for a short time was Amoco which had used nickel as an octane booster. (this was not Amoco white gas) as many people think. So anyway, the high speed jet sizes were increased by .001-.002" to richen the fuel mixture and I believe a 1 degree retard on timing. It's getting a little harder to remember some of these details!