Hi all,

got an advice to go with all round 3/16" lines. My problem could be caused by not enough fuel coming into the carburator.
About the plug, i was told that the OS A5 is a cold one and shouldn't be used (to be clear i was told by the Moki seller to only use A5 type plugs!). So i've bought a OS type F plug and a Enya N.3 (hot) plug. Will try both. But i am pretty sure that the advice was correct. In fact i had problems unplugging the 2V starter on the plug. The engine stopped working unless it wasn't really hot.
To answer to Lou55, the carb is well seated and cannot move except twist on its axis (probably to help a better setup of the fuel tube). I will double check the lines, but i'm pretty sure they are all ok.

Thanks to all!
BR