I have tried to get smoke on a .90 two stroke, it wasn't worth the effort. On the ground there is alot of smoke, but put it in the air and it looks like a slightly heavy exhaust trail. My next attempt is with a 1.8, we shall see.

That being said I have seen .52 four strokes pumping out tons of smoke, really good results. They had preheating coils wrapped around the outside of the muffler to get the smoke oil just a bit hotter before it actually gets injected into the muffler. I had a preheater on my .90 too but it didn't help much at all.