two ways to do this.

Run a Saito 125. take some souper soft copper tubbing of correct size. Run it 2-4 times around the engine cylinder near to top of the engine. get a smoke muffler. or coil more tubing around the muffler headerr and the muffler. Run your smoke fluid thru the tubing before it is injected into the muffler exhaust. remember higher pressure with a tiny hole to atomized the oil.
Now if you dont want to do that the buy this product!

http://aero-model.com/Smoke-EL-Carbo...arter-Set.aspx