Thanks Montague,

Here some more info. I agree that I should get someone to look the engine and see what's going on.

-I'm using 15% fuel, brand new that I bought with all equipment 2 month ago.
-Brand new glow plug, not sure which type it is, but also suggested by the store.
-Prop 10 x 6, like the first suggested by the store.
-I didn't use any procedure for the needdle adjustment but just changing a bit everytime and watching the results. I know I could use the pinch for the high speed (rpm should rise about 300 before engine dies if adjust is correct, right?). I don't have any for the low speed needle adjust. Which one should I use?
-The engine smokes, there is a brown liquid(mostly oil I guess) coming out and also can be seem on the link from the exaust to the fuel tank.

Just to add, sometimes the engine is idle and when you push the throttle like 10%, the engine sounds funny and dies.
I have some experience in car engines but don't seems to be adding anything to this fight!

Thanks,

Nilo