125+ Hours. Time for a top end job

[AZRickD]

That amount of blow by after just 125 hours is puzzling.

I consider myself a lugger on trail riding and even during some races. But a lot of our races have miles if fast sand wash and two combine tail with MX track.

[Jakobi]

Ahh the lectron! Little hot spot under looks about right. I'm yet to have a piston come out without a little glazing, but some have been run leaner than others for sure.

What exactly do you find interesting re the blow by? My latest piston at 65hrs shows much less, but the rings were at max spec and comp was notably down. Have you measured your end gaps?

[AZRickD]

I usually (always) have much less blow-by. Maybe a few millimeters below the rings. My normal routine is to swap out piston and/or the rings at under 100 hours just because I'm paranoid and like to see how things are going. That, and there is always a boost in power. This maintenence period is an outlier for me.

I guess the difference between say 90 hours an 130 hours is more than I anticipated.

The rings were just a titch out of spec.