Restaurants with sidewalk cafes will get their first rent increase in seven years when the District government raises the rents by 54 to more than 200 percent on June 1.

Under a city law passed two years ago, the city government, which owns the sidewalks, will begin charging all cafes 54 percent more. But enclosed cafes will receive an additional 100 percent increase because they stay open the year round.

The rent increase means that the owners of the Zebra Room restaurant, at 3238 Wisconsin Ave. NW, which had paid $610 a year to rent 559 square feet of sidewalk space for its enclosed cafe, will pay $2,170.

Across town, owners of the Market Inn, at 200 E St. SW, will see their $6,770 rent for 2,440 square feet of public sidewalk jump to $16,664 for the same amount of space.

At Armand's Chicago Pizzeria, the rent goes from $489 to $1,720 for 367 square feet of space for the sidewalk at 4231 Wisconsin Ave. NW.

"I think they outdoor cafe owners know they've been getting a pretty good deal all these years," said David Kessler, chief of the public space permit division of the Department of Public Works.

"It's still the cheapest form of rent in the city," said Kessler, but he added that he expects about 40 cafe owners to close their outdoor eating areas because of the increase.

The city will collect an estimated $1.2 million in new revenues, swelling the total public space rental collections from $1.7 million this fiscal year to $2.9 million for the fiscal year that will begin Oct. 1.

Washington sidewalks have been sprouting cafes since 1961 when Bassin's (now the address of the downtown Marriott hotel) opened the first one in front of its Pennsylvania Avenue entrance.

The number of cafes has grown from 85 in 1977 to 140 this year.

Outdoor cafes can increase a restaurant's business by as much as 50 percent, according to some city restaurateurs.

The rent increase is part of the Enclosed Sidewalk Cafe Act of 1982 that became law in April 1983 but allowed cafe owners 18 months to comply with the regulations.

The law creates specific guidelines for the construction of enclosed cafes. Under the law, the enclosed sidewalk areas can have no plumbing and must be temporary enough to be dismantled within 24 hours.

However, zoning attorney J. Kirkwood White, of the law firm of Linowes and Blocher, said the new regulations may be too harsh.

"I'm worried that this current law may go to far both in taxing and requirements related to awnings and enclosures," said White. "We want good-looking cafes, but obviously we don't want to discourage them. I think City Council needs to look at the regulations to see if they're going to be discouraging to business."

The city is raising the rent by basing its calculations on 100 percent of the market value of the restaurant property. In the past the rent has been based on 65 percent of market value. Enclosed cafes then pay that amount plus an additional 100 percent.

Since the rent is based on market value, small outdoor cafes in downtown areas such as Connecticut Avenue pay more than larger cafes in less expensive parts of the city.

For example, the Cafe Restaurant Splendide, which rents 299 square feet of sidewalk at 1521 Connecticut Ave. NW, pays $1,674 in rent.

But the Kentucky Fried Chicken, at Florida Avenue and North Capitol Street NE, where property values are less, pays $615 to rent more than five times as much space, 1,538 square feet.

The restaurant owners are supposed to pay their rent by June 30, but more than two-thirds are usually late, according to city records. Most are usually paid by Sept. 30, the end of the city's fiscal year.

In addition to the rent increase, restaurant owners with enclosed outdoor cafes were required to meet the new construction requirement last October.

"We still don't comply with the law," conceded Richard Tolbert, owner of Rumors restaurant, a popular gathering spot at 19th and M streets NW. Tolbert said half of his business is generated by the outdoor cafe.

"It will probably cost us $50,000 to redo our outdoor cafe to comply with the new regulations . . . . We'll redo it probably sometime this fall," Tolbert said.

City Council Chairman David A. Clarke said city agencies "are no more enforcing this legislation than they were before it came about."

Kessler said the regulations require more manpower for his department.

"I've been arguing with the city on this," he explained. "Enforcing these new regulations has turned into a full-time job because, by the time you have someone inspect 140 cafes each year to issue a certificate of use required by the new regulations , it's time to turn around and do it all again . . . . We could easily use one person working full time to enforce the regulations."

Less than 20 percent of the city's public space rent revenue comes from sidewalk cafes, said Patricia Montegut of the public space office. The rest is generated from rents on underground oil tanks and vaults. CAPTION: Picture/one: Cafe Restaurant Splendide rents 299 square feet of sidewalk from the District. ; Picture /two: Armand's Chicago Pizzeria owners now pay the District &489 a year for sidewalk space. Rent will go up to $1720.