World’s Fastest MX Bike – Kawasaki KX500

On May 17th, the #1471 Spectro Oils / Cardboard Robot KX500 ran 125.854 m.p.h. at the old Maxton Army Air Base! Timed by the East Coast Timing Association, Mark Wolbrink’s run is the fastest a stock, full height motocross bike has ever gone. It was also good enough to set a new ECTA 500cc record.

The guy standing on the left is Scott Guthrie...20+years ago he set a bunch of speed records with Yamaha TZ's....most still stand today!

The guy standing on the left is Scott Guthrie...20+years ago he set a bunch of speed records with Yamaha TZ's....most still stand today!

Along with Kevin Kilkenny’s 132 + m.p.h. run at Bonneville last year,  it doesn’t matter if the talk is about stock bikes, race modified or just guys tossing crap about the garage. The Spectro Oils / Cardboard Robot KX500 is the FASTEST dirt bike in the world!

Nearly 30 years ago, a 1981 KTM 495 became an urban legend when it was stopwatched at 123.75 m.p.h. The #1471 bike was built in the spirit of that big, old, air cooled two stroke and it’s rider, the late Rod Bush. We kept the stock carb and pipe, only tightening up the motor and changing the gearing, jetting, tires, and handle bars.

We got in a few runs between Saturday’s two rain intermissions. Just enough to sort out the bike details and to let Mark get familiar with the old runway‘s cracks and patches. Then, after it steadily rained overnight, we had a chance to hot lap the #1471 Spectro Oils / Cardboard Robot KX500 early on Sunday morning. We ’helped’ dry the track enough for the rest of the day’s racing.

Getting ready for a run down the old airstrip.

Getting ready for a run down the old airstrip.

With a bit less than a mile to get up to speed every little thing counts. Short shifting into second and third costs nearly eight miles an hour at the speed trap end.  After trying a couple of different variations on the ‘hefty guy tuck’, Mark found the spot and went 125+ on what would be our last run of the event. Sunday’s skies finally opened up and the event was called with a wet #1471 bike third in the staging line.

It was a hot, humid, and rainy weekend in North Carolina. Not the best air for a two stroke to breath, but the KX5 Power by Stewart motor made great use of the full synthetic Spectro Platinum 32:1 pre-mixed with VP Racing fuel. We had another great weekend of racing from this proven performance package and thanks to Decal Works the bike had a lot of show to match the go!

Even while we are focusing on the #3500 Spectro Oils / Cardboard Robot modified bike and the 2009 BUB event at Bonneville, Mark thinks faster is still possible from the MX bike. One thirty seems like the magic number and that should be fast enough to keep the kiddies from trying this at home. We really don’t want anyone to get hurt.

Remember, if you can’t catch um, you can’t stop um!

More information about the team, riders and both bikes, as well as action shots and event videos can be found at and soon The two Spectro Oils / Cardboard Robot KX500s are made possible by a partnership between Wolbrink Race and all our great team members: Spectro Performance Oils, Cardboard Robot, KX5 Power by Stewart, Moto-Werkes, Adambomb Gallerie, Decal Works, VP Racing Fuels, Glenn Curtiss Motorsports, Boca Bearings, Airtech Streamlining, SMR Magazine, Fuel Café, The Shop and Independent Environmental.

Laurinburg Maxton Airport
World’s Fastest MX Bike
Photos by Tara Bogart / GingerSnaps
May 16 & 17, 2009, Maxton, NC, U.S.A.

This story is about the full height KX500, the story from last year at Bonneville Salt flats is here




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9 thoughts on “World’s Fastest MX Bike – Kawasaki KX500

  1. I have a93 kx 500 that machine is sick and love what you have done .You guy’s are crazy love to be there

  2. why dont you be a man and ride the leadig bike ………..k.t.m………. because mine goes faster

  3. KTMs are over rated. You could ride a 789 pound 990 2 cylendar and go 125mph. Any KTM that goes 125+ means I’m a Chinese Jet Pilot. KTM’s 550 was more like a 400. I am an old KX 5honey guy. I have owned KTMs Hondas Yamahas Polaris(big mistake) Husqvarnas and Susuckies. I always go back to green. Stay green baby!

  4. I own a kx 500 not stock if it were an automobile it would be a full competition 427 cobra ismoke the hell out of 450 four stroks and everything else

  5. I have an 86 KX 500. I think they detuned them after that. This thing warps without a Chewbacca suit.

  6. I have a 1998 kx 500 and every time I ride it my fingers get stretched out and long due to trying to hold on. The meanest two stroke or any dirt bike I’ve ever ridden. Team Green

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