In his autobiography (Endless Highway), David Carradine describes Deathsport as a sequel to Death Race 2000, but set in the farther future. The DVD case has a reference to the year 3000, so I expect they were planning on calling it "Death Sport 3000" at some point.
It's terrible. It's so bad that Roger Corman strongly advised Carradine not to do it, but Carradine felt bad about having gone off to do Circle of Iron (which he always calls "The Silent Flute") so he did it anyway. And then Deathsport bombed. Horribly. It practically ruined David Carradine's career, although he bounced back a couple of years later with The Long Riders. His autobiography is full of movies almost ruining his career and other movies making him a big star again.
Anyway, this is a movie about motorcycles zooming around the desert while futuristic sound effects distract me from the action. I'm not one of those people that writes angry letters about how "the sound effects were clearly a four-stroke engine but that model of Honda only comes in a two-stroke and also the carburetor sounded wrong blah blah blah", but these don't sound anything like motorcycles. And yet, in spite of the "futuristic" things welded to the bikes, they're obviously regular motorcycles.
The swords they use are also obviously plexiglass. Carradine mentioned in his book that if they ever touched each other, they'd shatter, so they needed to come up with a whole new kind of fight choreography involving extreme closeups and extreme longshots. It's not very convincing (and it's sort of reminiscent of Star Wars, which came out the previous year), but it's better than the rest of the fights, where people get disintegrated to save the effort of using making them look wounded. Most of the special effects are computer generated, but they had to use the computers available in 1978, so it looks incredibly cheesy. Corman appears to have been shooting on video already, so that he could just flip a switch and make the screen blue. Blue means electrocution, I think.
To be fair, I should admit that there are some explosions and people on fire, so it's not like they were completely afraid to spend money. This was balanced out by the time-honored technique of just using the video control panels as sets for your high-tech scenes. For a good example of this, I direct you back to Star Wars Episode IV: A New Hope, where the planet-destroying beam is turned on by a guy who's obviously dissolving from Camera 1 to Camera 2.
I might as well mention at this point that the "Deathsport" in question involves "Death Machines", which are the aforementioned "motorcycles with jet sound effects". They drive around each other on a motocross course for awhile until one rider shoots the other with a disintegrator, which makes him vanish instantly. Futuristic!
Incidentally, you know that mountain in Bill and Ted's Bogus Journey that the robot Bill and Ted bring the real Bill and Ted to? The one that's in Star Trek and a million terrible science fiction movies? This is one of those terrible science fiction movies.