Evel Knievel enters his first and presumably last motion picture vehicle, "Viva Knievel!," lugging a large cardboard box that obscures him from view. His star qualities vanish the moment he lays this burden down and begins inflicting a heavier one - the weight of his loutish presence - on the audience.

Connoisseurs of the ridiculous are likely to find "Viva Knievell", now at a few area theaters and drive-ins, an irresistible sitting duck. It's not often, even in a medium as cordial to self-delusion and vainglory as the movies, that one has the opportunity to study such an imposingly disparity between the admirable image a performer supposes he's projecting and the disreputable one we're receiving.

Knievel himself supposedly suggested the plot, a filmsy excuse for motorcycle stunts and automotive chases on one hand and sanctimonious speeches on the other. A corrupt promoter played by Leslie Nielsen tries to lure the hero into a death trap and drug smuggling scheme down Mexico way. It's an index to the story's credibility and the star's charisma that one would just as soon see Nielsen and the other rotters succeed.

Knievel cuts the most unimpressive figure since an overweight Tom Laughlin waddled onto the screen in "The Master Gunfighter." Between his coarse, puffy features, his Norman Mailer or Italian tenor girth and his star-spangled, candy-colored costumes, Knievel is quite a sight. One doesn't expect the second coming of Cary Grant, of course, but the producers reveal their unwitting contempt for the public by implying the heroic aspirations can now be satisfied by a model as motley as Knievel.

"Viva Knievel!" seems to have been conceived in a spirit of abject flunkeydom. Like the producers of the scandalous TV special "Evel Knievel's Death-Defiers," the producers of the movie have vastly overrated Knievel's appeal. It will be a blessing for the star - and for Gene Kelly, Red Buttions and particularly Frank Gifford, who accepted supporting roles - if the film does a quick disappearing act.

The very idea of someone like Gene Kelly playing second fiddle to Evel Knievel is offensive, although it has led to a couple of funny moments, one when Buttons gets in a shoving match withh Kelly and pleads to Knievel, "Get this gorilla off me!" and another when Kelly drops Knievel to the turf with what appears to be a rather mild shove. Some tower of strength, you murmur, as Evel goes splat.

Interviewed by Bob Thomas during the production of the film, alleged to have cost $5 million but looking more like an amateurish $50,000, Knievel was quoted as saying, "Kids look up to me more than anyone else in the world." It's a boast with no visible means of support.