It's likely that something went missing when you took apart the carb?
That's what I discovered at least. The first time I took the carb apart, I hadn't realized that a tiny spring went flying across my garage never to be found again. When I put the carb back together and reinstalled on the bike, I had a similar issue to what you're describing. I had a forum member remind me to double check that I didn't loose a specific tiny spring that sets the needle in place under the spring seat cap. Turns out I had lost it. My problem was solved one I got a replacement and reinstalled.
My bike is a 2019, so a different carb style, but there are still those little springs that are easy to lose. Hopefully it's something that simple. Here is a diagram of the '87 tw carb:
Good luck. I hope you find your issue without too much more hassle.