Piston seizure pics. 4 corner seize? Causes?

Crank is fine. That discoloration is from the casting and machining of the rods.

4 corner seize can also happen if the midrange is too lean and you pull wide open and then back off to part throttle. It can also happen if the clearances are too tight, piston to cylinder wall.

When was the fuel filter changed last?

The DET hitting is interesting... I've seen DET come on when the filter was restricted, that is why I ask about the fuel filter.

sled_guy

Holy big pictures lol.

Just some thoughts. You never said year (I think). '13 is the most prone ('cause of fuel map) to this without a controller.
This is not a cold sieze to me unless the pistons were designed wrong. Know nothing about MCB.

144 psi? How did you not get det when you rode it?
I know gauges are different and like to think my old Snap On gauge is half close but at 1100',where I build, I found about 130 psi the limit for the fuel we have up here at the pump. 137 at home, 20% AV gas is required for me to ride 5000' to 6500' but a few add ons.

Det will heat the top of a piston faster than anything and barrel will take time to catch up (still tight) and continued det creates combustion temps that the cooling system can't keep up to (208F in 1/2 mile?). Too-hot-a-top 'causes the oil underneath to burn into carbon crusty's (your pic?).
I've see forged pistons expand quick enough and big enough from just light det to crack the barrel straight down from the back boost port to the base. Have a good look there.

Imo. I know I have enough oil when the puddle in the case is big enough to deposit oil on the crank webs as the engine is rotated. This is all "splash" lubricated in this area and above.
If one rod is different in color find out why. I check each line by removing the "intake end" off the pump, inserting the bandjo bolt with both washers and a 6 mm nut to tighten, then squirt to confirm flow with and ol' oil squirt can with two stroke oil though the bolt's hole.
Bleeding the oil is important if you take a tank off because bubbles can get stuck if you don't force them through in the beginning. Best in the shop on a stand Imo.
Good time to change the filter. Start with the tank installed and throttle bodies off. Use the bleed screw on the pump until no more bubbles (doesn't take long) (have you replaced the cap yet?) come out. Use a rag lol.
After the rest is installed, take a bit of wire, hook the pump lever, pull it up to full open and secure to the frame some place. Fire the sled up and let it idle while you put it on a track stand and get a fan pointed out the shop door. Then,,, throttle it up to 4 or 4500 rpm and run it until a neighbor comes over and asks whether they should call the fire dept. Should be bled by then and the motor will be so happy. If you live in the country, I wouldn't wait for the neighbor.

If I use forged pistons that are not OEM (like when I installed the MNTK kit on my Pro) I do this smoke show (without waiting for the neighbor) in my shop, before loading, for 5 rides just 'cause I've used stuff like Wiesco's in the past.
Kinda anal I know but zero failures using "kit" pistons since.