The only thing i haven't done yet is to swap the CDI but here in Bulgaria nobody has NSR250 and to do the test i must pay 300pounds for a used pgm in unknown condition.
Mc 18 R5k has the center seal integrated in the bearing like the mc21.
I will try to do leak down test the way you recommend.
Maybe the solenoids are not working and causing rich conditon ?
I am thinking of blanking the power jets and removing the solenoids.
At which cables i should apply voltage to test the servo motor ?
Greetings