So I am breaking in my 8-T RTR today. Once I got past the first slobbering rich tank and a broken starter box belt, I readjusted the HSN and LSN to 3 turns out. I was able to keep the temp at 200-220 with it still running rich and spitting fuel by putting foil on the head.

Everything was fine for the first 4 tanks, and I varied the throttle, didn't go crazy. I did a couple full throttle bursts for a second or two during tank 5, easing the throttle on an off - the usual stuff. After every tank I let it cool and would pour out the left over oil from the muffler, and it just looked like clean used oil.

Near the end of tank 5, it started sounding weird. The idle was just not right like it was going to die, which was strange because the rest of the break in the idle was no problem. Then the temp started going up suddenly from 200 to 230 - very fast. Before I could shut it down it flamed out. The piston was frozen and I thought it was just stuck at TDC but in fact when I turned it over I saw my mark for BDC at the bottom. I could barely move it a BDC and I thought the rod went or a bearing.

I used a screwdriver to move the flywheel but the piston was so tight at the bottom I thought this is not good. When I dumped the extra oil from the muffler this time it was grey - like there was very fine metal shavings in it. Again, I thought not so good. So I let it cool and put some after run oil and cranked it on the box and it turned over. I thought well either it is busted or it isn't so time to find out and run tank 6. Put in a new glow plug because they can do weird things when they are going bad.

I fired it up and it ran OK, again the temp was anywhere from 190- 210 - seemed fine and I leaned it to 2 1/2 turns on both needles. Seems OK now but the weird episode freaked me out a little bit. I ran tank 7 and no issues, so I guess if something let go I would know it. Anyone have any experience like this during break in?