In my experience when I posted my Buck Park Cabin camp and ride, the limit was 10 per post. How I got around this was: I would post around the 10 photo's. Staying in the thread I would then "add Reply" and continue posting about 10 at a time. It is possible that someone could have jumped in between my main post and adding replies, but no one did.
I didn't really think this was too big of a hassle once I figured it out. The one thing I would do differently next time is I would continue all of my postings as "add reply" to the main post instead of creating new post threads each day I posted. (i.e. eveining ride post, continued post, and final post). That way someone viewing would be able to view the whole thing in one thread instead of many (as I did). I think you have done similar in your build post.
Can't speak of the "limit", but perhaps it is a host protection limit of some kind.
I did view your Custom TW 200 Build "Blaster shock" thread section. I like the idea of that shock. Been a little disapointed at times with the stock shock as other have experienced as well...and the front, but all those mods will come later.