Originally Posted by weazelz

I would think that a 4-stroke keeps the unburned fuel-air mix better separated from the exhaust gases - something that two-strokes are pretty bad at. in the high temperatures of proper combustion the oil probably burns reasonably well/cleanly, rather than a portion of it getting burned much less efficiently/cleanly by contact the hot - but comparatively much cooler - exhaust gases. aerobatic aircraft make their smoke trails by dumping diesel into their exhausts, which makes the thick white smoke

doesn't make it a clever thing to do still. if you hadn't spent all you money on shiny blue & yellow shocks you could afford proper petrol