I've got a 1990, only issue it had when I bought it was second gear skips, and the kick starter was slipping. After reading online to use atf+4. So I tried that and issue was solved. I went for about 3 rides, all good. Changed the fluid again. New atf+4.
Next ride was fine, but as the ride went on it started getting harder and harder to find neutral and shifting between first and second started to take a lot of effort.
The clutch does drag quite a bit. I thought maybe something odd happened in there so did some investigating. Nothing was out of the ordinary. Checked the parts diagram. Everything is there and correct. Put it back together. New atf fluid again. Test ride and same problem.
Took it all apart thinking something was going on with the shift mechanism that's behind the clutch. Rear wheel up, it was having the same issue, I was spinning the wheel while shifting.
So then I started to think the shift forks are maybe worn or something. But on that 1 ride it went from fine to really hard to shift in like 2 hours. And too be honest most of the ride Im in second gear and not shifting a lot. So I doubt they wore so much just that ride.
So then I thought maybe it's the atf? I put some rotella 15w40 in cuz that's what I had on hand. Rode around the yard a bit and it slowly started getting better. And now it shifts fine and finds neutral quite easily.
Thoughts? Cuz I see people use atf for hard shifting kdx's. But mine seems the opposite? I'm guessing maybe the first atf change was ok cuz it had whatever left over oil on the bottom of the case still in there maybe? Maybe the shift forks like the thicker oil? I dunno.