This post is just FYI for those who may be interested. Just trying to do my part to keep TY alive during off season . As some you may remember, I posted back in March that my engine had deto damage at the end of this riding season. A little background ... Sled is '17 ZR9000 Ltd with about 5600 miles (225 hours). Tuned since day 1 w Stage 3 PEFI. Meticulously prepped and maintained. Stock air box. 2.5" straight-thru D&D stainless performance muffler. Stock fuel system. BOV. Silicon boost tubes. Intake boot spacers shortened; no boost leaks up to 25 psi. Rollover deleted from day 1. Gas mostly 92 octane w ethanol and this past winter 93 octane non-ethanol. Occasionally 91 octane (on trail). ARP head studs from day 1. Trail/lake riding mostly northern Wisconsin. Occasional multi-mile WOT. Coolant temps normal. At end of season I could tell when cranking engine was hurt. Compression test showed center cylinder about 25 psi lower than other 2. Fiber-optic camera inspection showed center piston with serious deto and other 2 pistons with some deto but piston over-heating evident. Piston valve relief areas showed they got so hot the aluminum had sagged inward causing top ring groove to open as the relief area tipped toward center of pistons. Also, because that area had tipped inward, the outer edge of piston was then in contact with cylinder wall. My rebuild is now complete. All engine bearings looked like new. No wear, no dirt, etc. Cylinder walls like new. No wear. No damage from detoed pistons. Top ring on center piston was ductile and had lost allot of it's temper due to excessive heat. To hopefully address piston over-heating, I sent pistons to Swaintech to get domes ceramic coated. I also used a drum sander on die grinder to carefully smooth and blend the sharp thin edges near valve relief areas. IMO, these thin sharp edges do not belong in a turbo charged engine as it is a natural place for excessive heat and deto to start. Used all stock Yamaha parts. Upgraded fuel system using kit from PEFI (larger pump, return line goes into basket). New and better tank strainer. Added a 10 micron high-flow post filter right before fuel rail to keep any debris out of injectors. Sent fuel injectors out for clean and flow. 2 of 3 were down 3.5% due to debris in inlet filters! Also going to try octane booster this next riding season although there is some debate as to whether they really work. Will avoid long (over 1 mile) WOT. IMO, cooling system on these sleds is designed for 200 HP not 280. Adequate for 200 HP at high duty cycle but not enough for 280HP for long pulls. Even without deto, pistons overheated (aluminum began to sag) just plain from being too hot. Coolant temps we see on cluster is temp of coolant coming into head from heat exchangers, not outgoing to exchangers. IMO, head gets so hot on long WOT pulls, coolant temps may be over 220-230! Pistons are cooled from below by oilers that spray into bottom of piston. At WOT for long pulls (1-2 miles with 280HP tune), this is not enough to keep piston cool. Pics attached. Note piston 2 has 2nd ring stuck. That's the way it came out. If you look at valve relief areas, you can see the sagging I mention. Engine had 5,600 miles tuned since day 1. Engine fresh and ready.