Re: the one time i impulse buy... (chinese motor kit)
I have many hundreds of miles on the KMC 415HD chain with no failures and it still looks like new, I use a Dupont dry film Teflon Chain lube and ride most of the time on very dusty dirt roads where I live with NO chain issues, I like the 415HD because it gives better tire clearance and holds up very good in my experience. but as always to each their own....it's all good if it works for ya!
I also as Kevlarr has said recommend hub regreasing, I recommend using a good "TACKY" MOLY BASED grease on the rear hub, and while you are at it regrease those front wheel bearings as well, that is the life of those bearings for sure.
I also recommend putting thicker thorn proof tubes in the tires this can save you a lot of grief and makes the bike safer too, 30mph front tire blow out not a nice thing, I had one on the rear go in the earlier days of my bike and it run me all over the road trying to stay hooked until I could get slowed down, the skid mark I almost left was not on the road if you know what I mean.....! so go with some good tubes.