This is one of those small issues where I'm just being a nice guy and saving you some money like I mentioned in the entry page. I can almost GUARANTEE that if you just got the bike and rode it 50 miles, this bolt is loose. The kick lever is 65 bucks, just mail 1/2 that to me and we'll call it even.

Just pull out the bolt, degrease everything, and put the blue Loctite to it. Two ideas to toss around that I have not tried are to tap the ks on before tightening, or even heat it (don't wreck the seal) before installing. It seems to be a thing where it wants to keep loosening up, so maybe it seats on further with use. Heating it first may cure that.

Another guaranteed loose bolt is the top subframe bolt. I installed a shallow locknut on mine.