Eight boxers with hopes of making the 1988 U.S. Olympic team will gain some important experience tonight at the Richmond Coliseum, starting at 7 p.m., in the first of two encounters being called the U.S.A.-U.S.S.R. Heavyweight Invitational Series.

The competition is for fighters in the three heaviest categories, light heavyweight (178-pound limit), heavyweight (201-pound limit) and super heavyweight (no weight limit).

Michael Liles, 23, of Washington will be one of five light heavyweights competing. The U.S. boxers will be coached by 1984 Olympic team coach Pat Nappi.

The other light heavyweights are Andrew Maynard of Colorado Springs, who is the U.S. amateur champion; Alfred Coles of Fort Hood, Tex.; Anthony Hembrick of Fort Bragg, N.C., and Joseph Pemberton of Camp LeJeune, N.C.

Ike Padilla of Yonkers, N.Y., will represent the U.S. in the heavyweight division. Riddick Bowe of New York City and Nathaniel Fitch of Fort Bragg, N.C., will box in the super heavyweight division.

Fitch, the 1987 national Golden Gloves champion, participated in a U.S.-Soviet competition in 1985. He is expected to fight Viacheslav Yakovlev, who finished third in the 1986 world championships.

The second part of the series will be held June 12 in Tampa, Fla.