This is an interesting issue. These may NOT be appropriate for, I am sorry to say it this way, lawn mower engines. I don't know how else to describe it, and I don't fully get what the issue but it is related to the fact that an alternator in a thiese kohler, briggs, motors are not as smooth in terms of electrical output as a better designed alternator. this is all heresay in my world. I can only say we bought LED replacement bulbs for the wifes Koler Commander powered craftsman and they burned out very quickly. I thought I had bought cheap stuff but got on the internet and read a few comments blaming the alternator design in the smaller engines.
I wonder if these sealed beam bulbs, with the big heat syncs, would perform better