How do you know if you're due a new piston/sleeve/crank?

As above really. Without waiting for some kind of catastrophic failure, how can I check if my piston, sleeve or crank are due for replacement?

I guess I could do a compression test to check for a worn piston/bore, but then again I'd expect a smoky engine if that was worn. The bike is running map3 with akro, so strictly speaking I should be following the competition schedule, but I'm no racer!

I've done 70hr on the bike, and have no idea how many hours it had on it when I bought it as the hr meter on the dash never worked. The odo is saying 1,600 miles but I don't think it's an original dash, as it shows that it's a Supermoto model on startup, and the speed/trip/odo is well out of calibration.

There's nothing wrong with the bike, I'm just trying to understand if I can do something proactively, without simply replacing components that still have plenty of life, just cos the manual says so...

Change in engine noise, loss of power, hard starting.......

The manual may specify a service interval but that is typically a pro racer/hard use schedule.

It all depends.

If you change oil, clean air filters, and don't keep riding with the radiators boiling over, you can get hundreds of hours before a rebuild.

Now, if you feel a massive lower end knock, or a death rattle, it is time to pull over and take the motor apart.

Of course, I had a death rattle once in my Yamaha WR444. I stopped immediately, towed the bike out and took the motor apart and found nothing but a tiny chip in the kickstart idler gear that would have fallen out in 10 seconds if I did not kill the motor immediately. I should have blipped the throttle instead. LOL!

The majob components will last along time if you never hit limiter . Checking compression will give you an idea .
Another point is to regularly check valve clearances . Once they've settled in they won't change a whole lot . If they change more than usual one day then it needs looking at closer . I've got mates that get 4 years out a a rmz450 and it's fine because it never sees limiter .
Every second on the limiter is ten minutes off its life