Same thing here with a KX 125, I burned the main and havent done 50:1 since. Any thing 250 and above even BelRay recomends 40:1 and 32:1 for 125's and smaller. Running a higher ratio means less oil is getting your mains properly lubed. I guess it all depends on how often you want to redo the top end. Or worse, spinning a main.showtime586 said:I spun a main bearing on a 250 a couple of years ago. I was using Motul at 50:1. I'm not 100% sure the ratio was the culprit, but I havent ran 50:1 since.