I'm with nuker, you will have to preheat the smoke oil for your best chance of getting good smoke. However, I too am not sure if it is worth the effort. I've seen .40 size models with smoke... could hardly tell the diff between smoke on/off.

I have a YS140L wit a slimline smoke muffler with preheat chamber. It smokes, and you can tell the smoke is on, but it isn;t very dense. Now my DA100 on the other hand will smoke pretty good, but that's a big engine. Even better, a 3W240 will really pump out some serious smoke.

The key to good (dense) smoke is heat. A 2 cycle .25 will not deliver much heat. I don't think a extra glow plug in the exhaust will come anywhere close to adding enough heat... couldn't tell if that was a serious suggestion or a joke.

Good luck anyway.