I just removed the head and am lapping valves because of timing problem. If I'm lapping valves, do I need to replace my piston rings too or not?
Car: 2010 Passat CC 1.8 TSI, 100,000 km
Absolutely not. One has nothing to do with the other. If there are reasons to change the piston rings, then by all means change them. Things like blowby and/or oil consumption would be reasons. Not because you pulled the head and are lapping valves.