i dont think you will find much diffrent between deisel and kero (as they are practically the same thing)

try picking up some special made smoke oil like superdry or somthing. you might get a better cloud.

also are you preheating the oil, are you just dumping the oil in the muffler or are you "spraying" it in. as atomizing it makes better smoke.

I'm new to smoke myself but i have already leanred a bunch of stuff needs to happen right to make the smoke system effecient