Hi, let me thank you for soluces i founded here.

Special thanks to Hypergobelin for his help.
I eliminated air links
I changed fuell line for onle with 1.5mm inner diameter
I tuned my engine
I used a cold glow plug
I used 30% nitro fuel

and my grandson (4years old) runned two tanks without stall.

Without theses advices, my Vulcan would be stored .