There is no FM antenna built in to the SA-80, So the literal answer to your question is "no".
Are there adjustments to improve the FM reception of the tuner section? Yes, but it is a task that requires fairly sophisticated (and accurately calibrated) equipment and considerable skill.
Finally, don't forget that the SA-80 was the absolute bottom of the line; it's not bad, but it's not in any sense up to the design nor performance standards of better Technics receivers, not to mention of their competitor brands. Indeed, at the entry level, IMO the SA-80 was the bottom of the crop of all of the major Japanese massmarket brands.
Now, if you're asking about the built-in ferrite rod AM antenna -- the best thing to do is to add an external long wire antenna (and a good ground)
or a good inductively (or direct) coupled, tuneable AM loop antenna. This WILL help. The vintage Select-A-Tenna is very good but no longer made (i.e., may be hard to find). There is a current production Terk AM loop that gets good press.
http://www.radiointel.com/review-2loop.htm
Here's a Select-A-Tenna in action, receiving WBZ-AM (Boston) -- a 50 kW AM station broadcasting at 1030 kHz -- at a distance of about 120 miles (in the daytime) -- no mean feat.
Onkyo T-4055 AM-FM stereo tuner receiving WBZ-AM (Boston) on a spring afternoon from about 120 miles away (& thanks to an inductively-coupled Select-A-Tenna!). by
mhardy6647, on Flickr
EDIT: Here are the innards of an SA-80:
SA-80guts by
mhardy6647, on Flickr
Compare it to the innards of its entry level contemporary the Pioneer SX-450 (15 wpc):
SX-450guts by
mhardy6647, on Flickr
Four entry-level receivers (from a couple of different model year "cycles", admittedly):
fourentrylevelers by
mhardy6647, on Flickr