More than two weeks ago, a Yangtze River-500 motorcycle and sidecar carrying a New York Times reporter, an American lawyer and a young man from Peking arrived in the tiny town of Zhenba in Shaanxi province of central China. The travelers headed for the town's only hotel, and so did local Chinese public security officials, puzzled over whether this peculiar trio had permission to wander in an area not open to foreigners.

Today, the Times reporter, 41-year-old John Burns, arrived at Hong Kong's Kai Tak Airport after being expelled from China because he had "broken into closed areas and engaged in espionage," according to the deportation order read to him by a Chinese state security official.

Before he arrived in Hong Kong, Burns spent more than five days in a padded cell in northern Peking's Baozhu detention center, held amid accusations that he had engaged in intelligence gathering during his motorcycle trip through northwest China.

During that time, Burns' detention has raised questions about the parameters of journalists' freedom in China and the motivation for invoking charges of espionage against a journalist.

Between that night in Zhenba and his airport news conference today, Burns said he has concluded that he "misjudged the extent of tolerance at this point in time in China, at least on the part of the authorities."

It was a misjudgment, according to Burns and others close to the case, that speaks loudly of the difficulties in gauging the depth of China's recent openness. The Burns affair seems to point up a tug of war within the Chinese bureaucracy over the pace of the opening up of China, according to Burns and to diplomatic and other sources close to the case.

These sources said the attention focused on Burns seemed to reflect tensions between the Public Security Ministry, China's police force, and the Ministry of State Security, an organization set up in 1983 to root out espionage. Modeled after the Soviet Union's KGB, the Ministry of State Security is said to contain China's most conservative political forces, who are known to be wary of the pace of the economic changes begun by China's leader, Deng Xiaoping.

Times' executive editor A.M. Rosenthal said in a Peking news conference that Chinese security officials had told him China had decided not to continue its investigation of Burns so that relations with the United States would not suffer, Reuter reported from Peking.

Burns, who was hurried from an early morning shower at the detention center to be told of his immediate departure, dismissed the charges of espionage. "It was nonsense from the start. I engaged in a quite legitimate journalistic activity," Burns told a group of reporters gathered at Hong Kong's airport this morning.

"I traveled through the countryside of China to see for myself, spontaneously, what differences have been brought by the reforms of the last few years," said the sometimes smiling, obviously relieved Burns.

Asked about a formal statement issued in Peking that said the trio "broke into a military restricted zone," Burns said, "I have no way of knowing what a military area is. It's not my job to inquire . . . . If inadvertently we traveled in military areas, our eyes did not betray it to us."

At a second news conference, Burns said he had long contemplated an independent, free-ranging journey through China's heartland, spurred by the tales of backpackers and tourists who spoke of roaming beyond the approved list of more than 200 open cities and meeting no resistance from Chinese officials. Burns joined up with Edward McNally, a 30-year-old lawyer teaching constitutional law at Peking University, and Zhang Daxing, who had recently returned home to Peking after studying at Middlebury College in Vermont.

"It was a blissful week. With nothing but a camera and a notebook, we experienced China. We talked to peasants. We didn't discover any secrets. We saw for ourselves, we chose who we spoke to," Burns said of the trio's motorcycle journey, planned to retrace a portion of the route taken 50 years ago by the American journalist Edgar Snow, which he described in his book, "Red Star Over China."

Burns admitted that he had neither made arrangements nor received permits to enter areas closed to foreigners. But he added that given the context of change in China, it was hard to know whether such permits were a necessity.

After returning to Peking on July 7, Burns said he had numerous conversations with officials of the Foreign Ministry and the Public Security Ministry. He said he apologized for not having the proper travel permits, assumed the affair was over and informed the Foreign Ministry of his plans to leave China with his family for vacation. Burns said he was taken by surprise when officials from the Ministry of State Security stopped him at the airport last Thursday and told him he was under investigation for espionage.

After 15 hours of questioning at the airport, and after his Peking apartment was thoroughly searched, Burns was driven to the detention center. He spent the next five days reading the Collected Works of Deng Xiaoping and occasionally being questioned by Chinese officials, while Rosenthal and Times foreign editor Warren Hoge arrived in Peking to press for his release.

Burns said he intends to remain for a time in Hong Kong, write about his trip and wait for his family to join him. The New York Times intends to assign a new correspondent to Peking as soon as possible.