What kind of grease do you use? It has to be thin enough to dissolve with chemicals. A bearing grease may be too thick.

 

I do use bearing grease, whatever is handy. Not too much, I don't pack it in or anything. Just a layer. It's thick enough so it sticks to the walls when the poston goes down, so I can wipe most of it off. Then final rinse off with brake cleaner/vac. Again, I don't use too much, just enough to wet it. I don't think brake cleaner would be good in the oil. And I doubt it's sensor safe. Of course neither is an issue on 2-strokes.