I own a himi 450 as well
Clocked over 7.5k Kms in 5 months
Including 40 % city ride and the rest indian highways
After bens video I checked my chain and I couldn't find any such issues at all
Been through every possible conditions
Rode the bike in monsoon season in the water clogged roads, in dust, off road, high speeds everything that you can imagine of
But did not faced any such issues
One thing I would like to mention is that I always keep my chain lubricated and well maintained
I do not use a chain lube or chain cleaner of any sorts, but instead I use diesel to clean and then 80-90w grade gear oil mixed with a little diesel to thin the lubricant as a chain lube. I would say it works like a charm
If you can figure just the right amount then it does not even makes much of a mess
Have been using this combination for couple of years now and must say it works like a charm