TOPIC:

I pulled my plugs after a long ride to montana and the 2 inside plugs have a yellow soot on them. according to my book this is due to heavily leaded fuel, but hasn't leaded fuel been illegal since the 1970's?

Contrary to popular thought, unleaded fuel is NOT illegal. Using leaded fuel in an unleaded vehicle IS illegal.

Usually you find one station in an agricultural town that sells leaded fuel. There are a lot of farmer who still use farm equipment that uses leaded gas. Having grown up on a farm I can tell you some of those tractors built in the 30's and 40's can literally run decades without needing an overhaul. I mention this because usually during an overhaul the old valves are replaced by new valves that can tolerate the unleaded fuels. The old valves relied on the lead content of the gas to lubricate them.

You may have inadvertantly refueled with leaded fuel. I have no idea how you could tell for sure. If I was there I could smell it and tell you. There is a distinct differance between leaded and unleaded fuel smell.

I know this because I grew up on a farm, not because I sniff gas for it's hallucinigenic properties.

I know it has hallucinigenic properties because of high school science class, not because I sniff gas.

I think that's all of the disclaimers!

I did get gas 3 times at a really ancient gas station near bozeman montana, the town had only 1 station and it had the old mechanical pumps, i guess that was probably where i got it.

Still doesn't explain why all 4 plugs weren't yellow.