How good are late 80's Japanese Fender Jazz's?

Pretty good, actually. Fender pulled itself out of its problems in the mid 80's.

 

It'll be just fine.

 

They are fantastic, but some tend to have dated styling. Lots of Japanaese Fenders of the era had no pickguard and kind of "updated" styling (P-Lyte comes to mind). Pickups may be great, may not be so great. They run the gamut. Always excellent construction and materials though.

 

If the one you're looking at is built anything like my '88 P, then you should have nothing to worry about construction-wise. As with any Fender however, you should still play it if possible to make sure you like it.

 

I have a mid to late 80's 4 string fretless Fender Jazz Special. It's great. Very stable neck. Nice tones. Absolutely no problems.

 

Supposedly the glory years for Japanese Fenders.

I've got one I bought new in 89. Fantastic bass. One of the best necks I've played. I did upgrade to DiMarzio model J's a few years ago, but I'll never sell this bass, definitely my "go to" bass when I'm sitting in the music room!