This U-150 customer had rebuild motor by himself but after engine run motor broken straight away. Let's have a look what happend.
#3 cylinder spark plug color show damaged piston.
Customer serviced carby but variable venturi diaphragm didn't fit proper because diaphragm didn't move as make lean fuel condition. 
Also customer forgot to fit valve and seat fix screw because V/S moved to up side as arm lifting stroke make too short. This is another reason for lean fuel.
#3 Piston top was damaged as melted. 
Another surprise, when customer put back carby assy he tucked oil hose between carby and manifold.
Lucky this #1 cylinder didn't damage because engine stop straight away.Good fun for rebuild motor and carbys by self but if you make a mistake will have a chance to more damaged and more cost to fix.
