125-200cc CR125 and 144 scored piston and cylinder (Pics and vid)

Could it be a jetting issue? Running too lean? I ride more high speed desert stuff at times.

A leaking LH crank seal could also cause a leaning out problem, but this should show on a leak down test.

Are you talking about a 5 gallon can? How much gas did you mix the oil with? 24:1 is 5.33 oz of oil to a gallon of gas......

24:1 is very oil rich, but will lean the air / fuel mixture. There is no reason you should have to go any lower than 32:1, and I doubt that you need more than 40:1 to do the job.

If it's gotten significantly colder where you are and you went to 24:1 with the same jetting that you had at 80 or 90 degrees, then that might be your problem.

Let me add, that if you need to run Super M at 24:1, then you should switch to 927 and back down to 40:1 or 32:1.

I'm running Maxima 927 at 45:1 without any issues. Not saying that you should run the say mixture. Most of my riding is single trail so not a great deal of higher speed work involved. I also have the 150 kit fitted.

The difference between 24:1 and 50:1 is not even a jet size so isn't worth considering as the cause. While 24:1 technically leans the air/fuel ratio, in practical application it is a non-starter. Opinions vary, but most smallbore engine builders agree that a high-RPM (desert) smallbore needs more oil, and 32:1 is generally the leanest they'll go for that use. I think Wally's mention of the fuel and oil possibly separating is an interesting and plausible theory. I have nothing to support it scientifically except that it looks like no-oil damage but you are sure you added oil. I would do a leakdown test and, passing that, switch both oil brands and gas station locations/brands. Go one up on your main and one clip on the needle to be safe and have another go. Make sure your silencer core isn't broken and misaligned, raising the pipe bleed-down pressure dangerously high.

If it was a lean-jetting caused issue or airleak-lean issue I would have expected it to have seized tight at least briefly, which you didn't mention if it happened. Or eroded the front edge of the piston and coated the headpipe in aluminum. It really looks no-lube galled.

Did you notice how much your connecting rod moved when you installed the 150 kit?

I just used the stock jetting. Temp was around 60's. So running that rich of a mixture will actually make it run hotter? I also read about riding WOT, and quickly closing it and allowing the bike to coast at a high speed is bad? I've been ridding 4 strokes for a long time and I actually used engine braking at times to slow me down. I'm riding the same way I would my 4 stroke. Can this be an issue?

This was after I used installed the kit, The manual stated 25;1 during break in. I was eventually going to switch to 32;1. Which the manual stated to use after break in.

My main now is 460. When you say go up, should it be in increments of 5 or 10? I will check the silencer. It's a Pro Circuit Type 296. While I was riding the bike stuttered, shut down, and a few moments later I kicked it over and it started up.

460 "should" be about right. Next up would be a 470. If you are holding it wide open for 10 seconds etc in cool temps don't be afraid to start at a 480 or so and work backwards. I ran a 490 in mine last year iceracing in 5f temps, holding it wide open for extended times. Start rich and work back.

Was it tight when it shut down or did the kickstarter move immediately?

With that rich an oil mix, it is hard to see how the bottom end could be that dry. Something happened to leave you with no oil film or residue.

It moved freely when I kicked it. I didn't kick it over right away. I looked down to make sure fuel valve was on, and choke was off. Maybe 30 sec to a minute before I kicked it back over.

I didn't measure those items. Interceptor or dominator?

How vigorously do I need to shake the fuel can? I will switch oils and rejet. Wally, can you watch my connecting rod vid one more time to be sure it's not that? Around the 47 sec mark, it seems to move back and fourth too much?

It was fine it has the usual side to side movement that I would normally expect from any 2 stroke. I would be more concerned with any straight up and down clearance in the big end bearing.

Zero up and down, and the movement of the crank feels butter smooth

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I will look into Amsoil, thank you. I figured since everything was brand new OEM it would have been ok?