I'm no expert on this subject. I am an expert owning metric bikes to include Hondas. That Grom engine will go for a long long time. We know that maintenance is important but there may be some components which may fail way before the engine. From my short time of ownership of the 125 engine, I've became aware that the timing chain tension system is a weak link. I guess if this was upgraded, you would have many pleasurable riding miles ahead.