It's what I have used (the plain 2s) for decades in many sleds. Started using it when I still took a lot of engines apart and you said why in your original post.
In my '13 pro (around 2200 miles total with 500 since MNKT install) it has been at 28 to 32 to 1 since hr 1 (maxed out adjuster and 100 to 1 premix). My original piston were in very good condition so it did it job on the walls. I did the ex valves twice last year and they cleaned up with a rag and my finger nail.
Not able to ride hard or much this year I just pulled the easy side (500 miles) to check a gasket I built and the valve was easy to wipe off. So was the gasket.
But,,, lol, I run cool with extra fuel where needed. Lean and hot, the Yamalube will coke up and need a couple of soakings with oven cleaner as well as some help from a plastic spatula lol.
That's experience from other ex valves and engines. If your burning Yamalube (or any oil) onto the valves you will help out the poor engine and probably add power by adding some fuel.
Poorest oil I ever tried for burning was Shell advance. Stuck well in the right places but needed mechanical help to clean up.
Poorest oil I tried for sticking to the right places was old Amsoil. Just finished and cleaned up a linered cylinder late one night and gave it a wipe with the guys "special" oil. Came back in the morning and the top 2 thirds was rusted with drips on the bench below lol. I'm sure they have changed things since then.
Hope it helps.
