Originally Posted by
Johny
How long is the lifespan of a ceramic bearing?
And when do you know if you need to replace them?
Depends, but... had some that survived to the practical life of the crankshaft without problems. You will know you need to change them when moving it with the finger it feels gritty.
The key for not ruining a ceramic bearing is to baby it (no high rpms, run them slightly rich) for around 3 or 4 tanks to allow it to fully seat on the bearing races and not spin the balls, if you manage to break-in correctly, the bearing will survive your engine.