''I don't regret setting bombs,'' Bill Ayers said. ''I feel we didn't do enough.'' Mr. Ayers, who spent the 1970's as a fugitive in the Weather Underground, was sitting in the kitchen of his big turn-of-the-19th-century stone house in the Hyde Park district of Chicago. The long curly locks in his Wanted poster are shorn, though he wears earrings. He still has tattooed on his neck the rainbow-and-lightning Weathermen logo that appeared on letters taking responsibility for bombings. And he still has the ebullient, ingratiating manner, the apparently intense interest in other people, that made him a charismatic figure in the radical student movement.

Now he has written a book, ''Fugitive Days'' (Beacon Press, September). Mr. Ayers, who is 56, calls it a memoir, somewhat coyly perhaps, since he also says some of it is fiction. He writes that he participated in the bombings of New York City Police Headquarters in 1970, of the Capitol building in 1971, the Pentagon in 1972. But Mr. Ayers also seems to want to have it both ways, taking responsibility for daring acts in his youth, then deflecting it.

''Is this, then, the truth?,'' he writes. ''Not exactly. Although it feels entirely honest to me.''

But why would someone want to read a memoir parts of which are admittedly not true? Mr. Ayers was asked.

''Obviously, the point is it's a reflection on memory,'' he answered. ''It's true as I remember it.''