you might have better luck in the offroad or mechanics section.
I am unfamiliar with the set up on that bike but you might wanna look at the simple stuff like the pads or shoes if its a front drum setup.
If thats all ok crack open a bleeder and see if you get any fluid out when you depress the lever, if not its most likely a bad master cyl but I WOULD CHECK THE OTHER STUFF FIRST
Since it's an '87, it's possible the master cylinder needs rebuilding. Try bleeding the brakes first, since it could probably use a good flush, and if the level in the master cylinder doesn't go down, you need to rebuild it. Good news: The parts are cheap, and with a service manual, can be rebuilt at home with a minimum of tools.
Don't look at the outsides of the lines. Take them off and blow air through them. If they've swelled, they will have swelled on the inside. Blowing air through will also blow out any clots of jellied DOT 3 that may be lurking in there.
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