[old jupiter]

Was surprised to find this old thread revived.

JKV, I like your collection. One thing I have that might be of interest to someone like you is an old dusty box of engine parts for a Harley Davidson (Aermachi) RR250 2-stroke roadracer from the '70s.

Rooster, what a cool car! Tell us more.

Hal, it's a shame our species is so dumb as to have over-produced our numbers by, at this point, a factor of ten or twenty. Otherwise we could have all of the fun old high-pollution stuff (steam locomotives, anyone?) and not hurt anything much.

Even today's conventional two-strokes are already a lot cleaner than they were in the '40s and '50s when the oil was "bunker C" at 12:1. Even then there was some question of how bad they really were. Kiekhaefer Corp. (Mercury outboards) did nearly all of their testing including long endurance tests on a small body of water, "Lake X," that they wholly owned down in Florida. When the early environmentalists of that time (1963, maybe) got the state to question Kiekhaefer, the company had an outside lab come in and sample the lake outflows. Tens of thousands of gallons of gas/oil premix (and this was the old oil, not the more recent 50/80/100:1 oils we got later) had by that point already been run through hundreds of 2-stroke outboards over several years. Furthermore, outboards at that time all had a little bleed hole in the lower crankshaft seal to drain excess oil that could build up in the crankcase at trolling speeds (a few years later this crude feature was replaced by a recirculator line that ran the excess oil back into the engine behind the carb).
Despite this, the investigation found no significant pollution, no rainbow-colored oil flows anywhere around the lake. My guess when reading about this long ago was that the fuel/oil comprised such light fractions that it mostly evaporated into the air . . . hardly desirable either, but in any case no smoking gun was found (and I forget whether lake sediments were looked at).

And again, those were early 2-strokes. 2-strokes got a LOT better (or less bad) in the mid-'60s and early-'70s. And they are now a lot better yet, with the new direct-injection Evinrudes, which others are striving to emulate. And soon, so far as can be seen from a very promising project that is currently undercover while patents are being applied for, there will come a variety of "radical" 2-stroke that is a great deal cleaner yet, as well as more fuel-efficient. So the environmentally-incorrect ring-dings of our grandfathers' day have less and less to do with current technology as the years and decades go by.

. . . which is fortunate, given the awful destruction we have already visited on the natural world.