Because Sugar Ray Leonard long ago stopped fighting primarily for the money, we can expect him to be properly motivated for Ayub Kalule Thursday night. A title, after all, is involved, even though the WBA junior middleweight champion hardly packs much punch.

Probably, this Ugandan now living in Denmark is tougher than casual fight fans believe. Good enough, it says here, to carry the fight past 10 rounds, possibly to go the distance. But of all the prefight questions about Leonard by nearly everyone except Bob Arum, none involves his losing.

Promoter Arum does not give Leonard the slightest chance of winning. To anyone who will listen and through every device possible, Arum sees the poor little Sugarman melting at midring under the onslaught of Kalule. Leonard knows Arum for what he is, that any objective talk costs him dearly.

"Just a promoter," Leonard huffed. "As far as knowing the true physical aspects of the game, he does not know." Then he gave Arum a verbal cuff, saying: "But who cares anyway?"

Which is central to Arum's blathering. He is caught in a pitchman's bind, trying to hype what most boxing fans see as exercise not worth paying for before the bout they covet. Leonard vs. Thomas Hearns Sept. 16 in Las Vega. Loud as he screams, Arum cannot twist talk from those two men going against each other in less than three months to their fighting on the same Astrodome card in less than 24 hours.

Because Mike Trainer dared look ahead to Leonad-Hearns Tuesday and a local paper printed it, Arum threatened a lawsuit today.

Can 't happen, Trainer said. "He's already called me an idiot, and you're not allowed to sue somebody that helpless."

Leonard has promised not to look past Kalule, that he will take this fight one punch at a time, and he doubts he and Hearns will try any gamesmanship, that one will want to demolish his opponent faster and more impressively than the other. In the next breath, he seemed to be trying to jab at Hearns' mind.

"He has to put on a better performance than me," Leonard said. "He has nothing that I want; I have what he wants."

Each is a champion, with an equal share of the welterweight title. Explain that last boast, Ray.

"He's just a champion. He's not marketable, hasn't got the notoriety or recongition. All of that. And I believe it leads to a bit of envy in him and creates a bitter climate. I pretty much feel he wants to be in my footsteps."

If Leonard wants to be considered as much a fighter as a personality, he is not bothered that his rings skills often are underpublicized. It provides the sort of prefight incentive no longer possible for a man who has earned an estimated $21 million by age 25.

Had he to live his boxing career again, Leonard would make just one adjustment.

"I think as an amateur I pretty much stunted my growth by trying to stay at 125 pounds for two or three years," he said. "I'd weigh 140 or 150 and sweat down to 125. I think I really hurt my body chemistry by trying to maintain that weight for so long as a young teen-ager.

"I think I'd have been bigger and a lot stronger if I handn't been constantly losing weight, that my legs would have caught up to my upper torso." c

Still, he feels comfortable moving from the 147 -- pound welterweight class to fight Kalule at 154. That is the main intrigue, how long and how well Leonard can carry those extra pounds.

"I walk the streets at '52 or '53 maybe even '55," he said. "My size is very deceptive. I don't look big, but I'm carrying solid weight. I'm fortunate to be between weights (welterweight and junior middleweight), so I can make either of the two with ease.

"I feel really strong, that I'll be a lot more effective with my punches. Kalule said he's bigger, so he should be better. Not true. I've fought middleweights, and I've fought well against them, been the dominating force. Marcos Geraldo (who Leonard beat in a rugged fight in May 1979) walked into the ring at 165. I was 151."

Determined as he is to leave as gaudy and lasting an imprint as possible on boxing -- he mentions 1984 as a possibility for retirement -- Leonard senses some limitations, that the Sugar Ray history honors most will be Robinson.

"I don't think I can ever get past him," he said, "and I won't even try. He's been such a name for so long, that quite naturally they'll identify with Robinson. The older generation.People now will see me in an airport and say: 'Hey, did you see Sugar Ray Robinson walking by just now?'

"People come up to me and say: 'Mr. Robinson, can I have your autograph? damn, you look good.'"