All the manuals on the forum can be found by clicking Browse / Downloads . on the list on the right click "and 9 more" to bring up the rest of the service manuals in the list. Here is the direct link to the Honda 4trax one you want :

Yes, it's a 1990. I have a 1991. There is a pdf of the service manual for it in the downloads section of the forum. I bought mine used 5 years ago, and paid a lot more than $200.... LOL.. You got a great machine if it wasn't abused. They're solid full time 4x4's with all the power all but the extreme riders need. They'll top out around 45 Mph if you really want to push them. One thing you want to check is the splines on the rear axle hubs. They wear out over time, especially if the hub nut was not kept tight enough.. I had to replace the rear axle and hubs on mine. The splines were worn out to the point ther left hub spun freely on the axle.