You have a resignating vibration problem and you have to isolate it otherwise you will have the problem regardless of the motor.
1) cowl screws - I would tapp holes, incert plastic pushrods for the cowl screws to hold and this will remove medal to wood contact
2) tank is it isolated as best as possible from vibration.
3)Take a thin bicycle tube cut thin strips line the portion of the cowl that touches the wood.
I believe the tolerance of the cowl screws is not securing the cowl in the best manner , then you run the engine, the cowl vibrates and generates vibration thru the fuse and that impact the fuel