Might be something lost in translation here- but are we taking about one of the Euromac Timberbears?
In America (where most readers are from) the Timberbear was a model based on the metal cased 600 series saws.
I believe the Euromac Timberbear was an 849? Plastic cased clamshell design of 49cc's?
Anyhow, the fuel line should come up out of the tank to a purge valve and to the carb- might run under the carb, but is not under the engine.
Perhaps you are replacing an impulse line that would run from the bottom of the cylinder to the carb- but not carry fuel?