FOREMAN'S (SIDE)SHOW MUST GO ON : 47-YEAR-OLD MEETS NEXT FOE IN JAPAN.

Byline: Michael Rosenthal Daily News Staff Writer

Many people, particularly those who once marveled at the remarkable skills of Sugar Ray Leonard, are bemoaning his return to the ring at 40.

George Foreman isn't among them.

``Why should he stop (fighting)?'' Foreman asked this week at the Los Angeles International Airport as he awaited his flight to Japan, where he fights Crawford Grimsley tonight on pay-per-view TV.

``One of the most awful things that can happen is to have a burning desire to do something and not do it because of what people may say. If he can conquer that and just come out and do it, the thrills are just unbelievable.

``When he gets back into the gym, when he's skipping rope, when the camera's on him, he's going to be aliiive.''

Foreman, 47, should know. In spite of what some might think, he's very much alive - in and out of the ring.

It will be 10 years in March that he ended a 10-year retirement by fighting - and knocking out - Steve Zouski in Sacramento. He was 38 then, already considered an old man by dubious boxing people and fans who gave him little chance to succeed.

Well, Big George has succeeded in a big way.

In the ring, at 45, he did the impossible: He knocked out 26-year-old Michael Moorer to win a share of the heavyweight championship he lost to Muhammad Ali 20 years earlier.

Out of the ring, he has become a folk hero whose endearing schtick has landed him a couple of book deals, a short-lived sitcom, a myriad of endorsements and other lucrative gigs.

And, it seems, there's no end in site.

``George is here and he's here to stay,'' Foreman said.

Foreman is no great fighter, not at this point.

Even at his peak, in the years he pulverized the likes of Joe Frazier and Ken Norton and seemed unbeatable, he was crude and slow but immensely powerful. Today, he's cruder, slower but just as powerful - too powerful for the vast majority of heavyweights.

Take Moorer, a skilled fighter who has the one thing you can't have against Foreman: a weak chin.

On that memorable Nov. 5 in Las Vegas, Moorer beat Foreman to every punch - except one, a straight right hand to the kisser in the 10th round that made boxing history.

``To work as hard as I did, to sacrifice, to have people laugh at me and then go out and win the title again, that was the greatest thing,'' he said.

``I did it. No one gave it to me. There was no waiting for a decision. It was a clean knockout. No one said the ref counted too fast, too slow. I did it. And it made me feel good.''

Which is how George makes other people feel. And why, in the words of longtime friend and publicist Bill Caplan, he's become ``a money machine.''

In career No. 1, Foreman was an entirely different person. He was moody, often surly. He was the new Sonny Liston, a brooding, menacing figure who was anything but fun.

The second time around, older and a lot wiser, he took a page from from the book of an old nemesis: Ali. He saw the value of selling himself and has lifted the art to dazzling heights.

According to Forbes magazine, Foreman, who fought only once last year, nonetheless made an estimated $18 million last year in prize money and endorsements - No. 6 among all athletes.

The $8 million he made in endorsements is the most ever by a boxer.

``It's a product of the old-time PR guys,'' Foreman said. ``They used to go out and do radio shows, hang posters, stop by TV stations, really ask for interviews.

``I learned from the bottom up, this old Barnum-and-Bailey thing, how to sell yourself. There's a whole generation of boxers out there who don't know anything about it. I knew that if I could get out there with what I know I could blow these guys away.''

Or, as he told Forbes: ``I'm not the best fighter but I'm the best salesman in the world.''

When will he become a full-time salesman?

After Grimsley, an unknown who should pose no threat, Foreman said he wants to fight overseas - possibly against Tommy Morrison in Australia - and close out his career in his hometown of Houston.

That might not be the end, though. See, there's some unfinished business.

First, Foreman considers himself heavyweight champion because he didn't lose his title in the ring. He was stripped of it after he outpointed Axel Schulz and refused to give him a mandated rematch.

And, second, he longs to fight Mike Tyson, whom he has baited for the past few years in a futile effort to land the richest fight in history - a fight he truly believes he would win.

An example: ``Mike Tyson doesn't want to fight me. I'll use the word `scared.' I'm not trying to say he's literally frightened of George Foreman but he's scared to do this and I don't know why.''

So when do we see the last of George Foreman the boxer?

``If someone knocks me down, I'll never fight again,'' he said. ``I've been back 10 years, and no one's knocked me down. If someone whips me, I'll never fight again.

``You know what's strange, though? Other guys, like (Buster) Douglas and Tyson, get knocked down and people say, `Oh, you'll be back.'' I win the title and people ask, `How long will you be around.'

``I resent that. This (age discrimination) starts with boxing but where does it end? Hey, I'm here, I'm alive, I'm competing.''

And, in so many ways, winning.

FOREMAN VS. GRIMSLEY

Who: George Foreman faces Crawford Grimsley in a 12-round heavyweight bout. On the undercard, Tommy Morrison takes on Marcus Rhode in a 10-round heavyweight bout.

When: Today, first bout at 6 p.m.

Where: Tokyo, Japan. (The card takes place on Sunday in Japan.)

TV: Pay-per-view, suggested price of $49.95.

CAPTION(S):

Photo, Box

Photo: (color) George Foreman

Box: FOREMAN VS. GRIMSLEY (see text)