RUSSIA AND THE SUMMIT AFTERMATH : NEWS ANALYSIS : ‘Big Boris’ Gains Needed Stature With Americans : Visit: The Russian president’s ecstatic aides say his trip was even more successful than they had expected.

MONTREAL —  Nobody had a more succinct view of the results of this week’s U.S.-Russian summit meeting than Naina Yeltsin, the Russian president’s wife.

Watching her sweating husband take the wheel of a combine and hack a circle through a sunbaked field of Kansas wheat, she acknowledged it was the first time he had ever driven a combine but added, “He can do everything.”

After this week, how many Americans would disagree?

Boris N. Yeltsin leaves for Moscow today after winding up a visit to North America with a stop in this Canadian city. In four days in the United States, he convinced American officialdom that he means what he says about enacting reforms, and if his jaunt to Kansas two days ago was any barometer, he convinced a good part of the citizenry, as well.

“Big Boris,” as Sen. Bob Dole (R-Kan.) affectionately dubbed him, never looked more like the capable leader of a great country than this week. Yeltsin was guilty of only a bit of hyperbole when he boasted, “In two days, we achieved more than what had been achieved in decades.”

Thirty-three documents were signed after his talks with President Bush, Yeltsin crowed, some of them diplomatic filler but also a spectacular arms-reduction agreement.

Even Congress, obsessed with its own scandals and election-year worries, gave the big, white-haired man from Siberia a hero’s welcome--an action, it is true, that cost them and U.S. taxpayers little or nothing. But Yeltsin’s straightforward, impassioned appearance in the House chamber could win him the biggest prize of all--rapid passage by Congress of a bill that would provide billions of dollars in credits and other forms of aid to give Russia’s needy economy a shot in the arm.

As they prepare to leave North America, members of Yeltsin’s entourage believe their man did everything he came to do--including showing Americans that they can count on yesterday’s populist maverick to bring the process of democratic change and free-market reform in Russia to fruition.

“I think he did more than expected,” Yeltsin’s press secretary, Vyacheslav V. Kostikov, said in an impromptu news conference during Yeltsin’s visit to the Kansas wheat farm. “I think Congress will now approve the aid.”

To gauge the magnitude of what Kostikov called Yeltsin’s “stunning” triumph, one should recall the atmosphere before the Russian president landed in Washington on Monday.

Reports then abounded that the former Communist apparatchik had slammed the brakes on the reform process, that he and his allies might be losing their grip on power, that Yeltsin was ill or once again the “Boozin’ Boris” of yore.

When he stalked off a Moscow tennis court during a pre-summit television interview, Russia’s paunchy president seemed again to be the old, unpredictable Yeltsin--the same erratic hothead who, as a boy, blew two fingers off his hand trying to take apart a stolen hand grenade.

(For the record, Kostikov said his boss had been offended by an unspecified “rude and unacceptable question” from an interviewer.)

But once Yeltsin crossed to this side of the Atlantic, Americans saw a straight-talking, painfully earnest Russian who told his hosts that his dearest goal for his own people is to help them live as well as Americans do.

In what appeared to be the first U.S. movement in reaction to Yeltsin’s performance, the Bush Administration was reported to have called on the International Monetary Fund to ease its demand for a rapid end to remaining government involvement in the Russian economy--a requirement Yeltsin told Bush could have “fatal” consequences for the long-term success of his reforms.

If the IMF moderates its demands, that would mean faster access for Russia to an aid package totaling $24 billion that has been put together by the United States and another six of the richest capitalist nations.

As for Congress, despite all of its applause for Yeltsin, its seal of approval for U.S. emergency aid is not yet in the mail. Dole, the Russian leader’s host in Kansas, predicted the matter would come up next week in Congress but acknowledged, “There are going to be some ‘no’ votes, you can bet on it.”

It is hard to describe Yeltsin’s first official state visit to America as anything less than a triumph. In a victory that was personally important for him, he apparently banished nostalgia for Mikhail S. Gorbachev from American hearts. In retrospect, he even managed to turn his biggest tactical error to his advantage.

His hand clasped to his heart--a gesture of sincerity that became familiar to Americans during the visit--Yeltsin pledged to Congress that if there is a single American POW still in Russia, he will find him and return him to his family.

It was a public-relations masterstroke, and it extinguished the storm that Yeltsin unwittingly ignited by mentioning the POW issue in the first place.’

“He had just wanted to go to the end of the truth, to tell all the truth,” Kostikov said.

When Yeltsin left the United States, his entourage said his relations were now excellent with Bush--a leader who once had not wanted to receive Yeltsin at the White House when he was the main political thorn in Gorbachev’s side.

But Yeltsin’s dazzling success at summitry cannot eclipse the problems he faces back home. He will return to Moscow to face criticism from some circles that, with the new U.S.-Russian arms accord, he has given up the backbone of the Russian strategic arsenal, the 10-warhead SS-18s, without receiving enough from the United States in exchange.

Likewise, it is too early to tell whether Yeltsin’s pleas to U.S. business to sink “hundreds of billions” into Russia’s shattered economy will stir any action. Although Yeltsin moved recently to adopt new regulations to improve the climate for foreign investment, key questions on issues such as taxes and land ownership remain without clear answers.

But that is a battle for tomorrow. For the time being, he and his entourage are savoring their victories on Capitol Hill and in the wheat fields of Kansas.

“For the first time, I think, the peoples of America and Russia have become friends,” Kostikov said.