Hello all, I bought a used, defective scooter about three months ago (Piaggio NRG Purejet with injection system) and now I try to get it to run in vain. Maybe one of you can give me a good tip? The engine has a compression of only 4.5 bar (to be 8-10bar) and therefore it does not start. What have I done so far? – Piston rings, pistons and cylinders renewed. – Cylinder head separately pressed, it is dense. – Simmerrings left and rec ht renews – engine searched for leaks and hair cracks, found nothing. What can it be that the engine does not build compression?