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KTM Supercross – the bike that made history

1997 KTM 540SX

The 1997 KTM LC4 540SX Makes AMA Supercross History

Lance Smail, Tom Moen and KTM ride their way into the record books.

In many ways 1997 doesn’t seem like it was all that long ago. It was an exciting time in the motorcycle world.  Mike Lafferty was on his way to winning his first National Enduro title for KTM. Meanwhile in the moto world, undisputed champion Jeremy McGrath decided he couldn’t come to terms with the highly anticipated new aluminum framed Honda CR250.  So Jeremy jumped to Suzuki and Pro Circuit’s Mitch Payton destroyed a mountain of cylinders trying to get the anemic RM250 to run with the big boys. Jeff Emig seized the opportunity and took the reins of the Supercross championship. Although in truth, McGrath suffered a number of incidents, both on and off the track, which contributed to his runner up position in the championship that year.

The entire world was abuzz with rumors of the forthcoming four stroke revolution. There was plenty of speculation, but little evidence of it had hit the showroom yet. Joel Smets was campaigning practically the only true thumper race bike, the Husaberg, on the world GP scene. Here at home there was a burgeoning national four stroke mx series that was gaining lots of attention. The problem that faced the riders was trying to find a suitable bike to race.

At the time the most popular thumper in the country was the Honda XR400. It wasn’t revolutionary, more just a good use of existing technology to produce a great all around trail bike. While it is one thing to convert a trail bike for off road competition, it is very much another thing to try and make into a full blown motocrosser, the whole silk purse thing.

So the starting gates of the four stroke nationals were a mix of European race bikes, like the Husaberg, KTM and Husky as well as the modified trail bikes like the Honda XR400 and Kawasaki KLX650. These had been pushed to the very limits to produce maximum horsepower and handling.  Team Green put together a very trick KLX250 for Ty Davis to ride, but with only 340cc of displacement it saw limited success against the big bore competition.

During the 1996 race season, the four stroke national series made a couple of appearances at the outdoor mx nationals. With Lance Smail at the controls and Tom Moen spinning the wrenches, KTM was well on their way to winning the four stroke title. During one of the events, company boss, Rod Bush, noticed that the team’s lap times were very close to those of the premier 250 class. This got him thinking about the idea of actually competing in the premier class the following year. So he gave the challenge to Moen:  build a competitive, Supercross legal version of the four stroke national bike. Hence the 540cc displacement, to comply with the AMA rule book.

I stumbled across this little piece of history sitting in beautiful “as raced” condition at the KTM headquarters in Temecula while dropping off a test bike. This bike has a special meaning for me and a unique place in the record books. This is the very first thumper to qualify for an AMA Supercross main event.

Looking back at the first versions of the prototype Yamaha YZM400 that were raced here and in Europe, those were very trick bikes that featured an array of exotic hand built and one-off parts. By contrast, the KTM seems amazingly stock. Most of the major components are the same as what came on the showroom version of the model. Frame, wheels, brakes and most of the controls are all production pieces. The seat and body work is lifted from the two stroke 250sx model and wrapped around a handmade aluminum fuel tank.

Probably the most obvious piece of eye candy is the 50mm Marzocchi Magnum conventional fork that featured factory twin chamber internals. This is right before KTM’s switch the WP Extreme forks. There was a fast paced development in fork technology at the time as both these suspension makers had returned to the conventional design and were working to prove it better than the inverted design. Coincidently, Showa and Suzuki were trying to do the exact same thing that year on McGrath’s bike. But this would be the last season that Suzuki would try to race at the top level with the conventionals.

Ultimately the Marzocchi and WP conventional units would only last another two years before being dropped for the more popular upside down units. It seems strange that while tube size had grown clear to 50mm, WP would drop back to 43mm for the next generation USD models before later increasing the size to the now standard 48mm.

The bike runs with no air box, just a standard cylindrical foam filter clamped to the Dell’Orto carb that has been lifted from a Husaberg. Internally the motor is mildly hot rodded and has a three speed transmission. The 540 also features a custom exhaust that exits on the right instead of the original production version on the left. This is capped off with an FMF muffler.

Now we jump forward to the start of the New Year.  It was January 11, 1997 at round one of the AMA Supercross series held in the Los Angeles Coliseum. The world was consumed by the Jeremy McGrath saga and everyone was screaming to see his debut on the Suzuki. His former teammate and 125 champion, Steve Lamson, got to take over the number one position on the factory Honda.

For those of us in the nose bleed seats at the coliseum it was a bit difficult to keep track of all the qualifying action. Then from out of nowhere it came, that booming sound of a big bad screaming four stroke. This was way before any noise rules came into existence. It was hard to pick out the actual bike from way up in the stadium, but soon I could see the dark orange of the KTM. It caught most of us off guard; we had never even considered that a thumper might try to qualify for the big show.

The drama that unfolded the rest of the evening was overshadowed by the coming of the four stroke. McGrath would go on to have a mediocre first ride on the RM250 and his former team mate Steve Lampson would punt him once just for good measure as they both battled for mid pack finishes.

So you might say this was the start of the revolution. With four stroke ace Lance Smail at the controls of the booming bike, history would be made that night. He would go on to have strong year in the outdoor nationals, even battling with Dough Henry on the Yamaha factory prototype YZM400. It would be another year before Henry would make the Supercross debut of the production version of the Yamaha and in doing so, ensure the future of four stroke motocross racing for years to come.


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  1. Thanks for posting this. i really enjoyed reading this.

  2. Beez says:

    Great article and photos. I hope you don’t mind but I shared it on facebook and ADVrider.com. I was at that race and remember it well. The fans were just going nutz for that big booming KTM. I just sold my ’97 620 RXC this year and was always proud that it share the family tree with supercross, rally, supermotard, enduro, flatrack and hillclimb racebikes. Was there anything the LC4 couldn’t do?

  3. Chilly says:

    And from Scott Wallenberg:

    Actually in 1972 and 1973 at Daytona MX, a Harley 350 Sprint was ridden by Harley employee Ken Johnson who was spearheading the development of the rear forked MX bike.

  4. Chilly says:

    Joe Bonnello writes:


    Great piece on the KTM, that bike is bitchen.
    But, it is NOT the first four stroke to qualify for a SX main by many years.
    But first, ssssshhhhh, don’t tell Moen as he is very sensitive about it. You know how fragile the poor boy is.
    Actually, The Rocket, Rex Staten was the first four stroke to make the main at Daytona SX in 1974.
    I know, I was there! He was riding a special Honda CR250 Factory bike with a trick big bore XL350 motor shoe-horned into it!
    Might have been a Bill Bell motor. I remember it was beautiful, and Wreck It Rox finished fourth or something overall.
    There were three motos in SX back then!

    Also, in 1972, I believe, kinda foggy ya know, the great Rich Thorwaldsen (RIP!) rode a Rickman BSA to Top American at a Friday night TransAm race at Ascot park, no shit!
    I forgot what he did but it was either second or fourth against all the top Euros.
    Not an official Supercross but Ascot and Lions were really the start of indoor stadium racing in the USA.

    Bitchen web-site!

  5. Tony G. says:

    Great story, Chilly.