sad news :
after starting engine , this one doesn't run correctly (n°3 cylinder not efficient and I have some returns in n°1 carb (I can see sometimes gaz pressure going into the vacuum pipe or exhausting across the carb port at slow down rev speed)
I have tested the pressure and 1 cylinder is 2 bar less the others
after undo the cylinder head, this is what we can see:
1 piston has visibly heat a valve... and another is different and looks new
I decied to rebuilt the engine... the bores are wear of 0.2mm
my engine lifter was too short to access to the engine !
I made something else who made the job ! :