Short-Track Special

American FLYERS

SHORT-TRACK SPECIAL

CZ into C&J

WHEN BILL CULVER, OWNER/OPERSTOR OF C&J Racing Frames, suppliers to the AMA’s Grand National teams, showed up with a vintage CZ motor sculpted into his latest dirt-track frame, our crew collectively asked, why?

Because the sum is greater than the whole of the parts.

But first, the parts.

Younger readers won’t remember this, but when motocross arrived in the U.S., the sport was astride two-strokes from Europe. They blazed past the Yank and Brit four-strokes faster than you can foul a sparkplug (which they also did regularly).

CZ, the Czechoslovakian brand, was arguably the best, as in four straight world 500cc titles in the ’60s and Brad Lackey’s first national title here in the ’70s. CZ had good people in the U.S. and built a following, still active as we’ll see.

One such CZ fan is Scott Richert, from St. Clair, Michigan. Some years back, a racing buddy gave Richert the engine seen here, a 380cc Single, and made Richert promise to do something worthy of the powerplant’s heritage and strengths.

The friend died before his time and Richert puzzled over how to keep the pledge.

The CZ 380 was as good as engines got back then, and it seemed to Richert that an improved version (many vintage engines are better than new nowadays) would work in a modern chassis, for instance a C&J monoshock.

As luck had it, C&J s Culver rides a restored CZ in vintage motocross. He was pleased when Richert commissioned a Pro-level frame and suspension for the older engine. Better still, the CZ guys all know each other. It seemed wasteful to ship components back and forth, from Michigan to California, so the engine went to CR Racing in Fallbrook, California, just up the road from the C&J shop in San Marcos.

CR’s Charley Richardson rebuilt and retuned the engine. The cylinder was reworked, nine ports from seven, with a reshaped combustion chamber, a reed valve for better top end and a hydroformed exhaust system from TC Exhausts in Hemet, California. The oddlooking carburetor is from a snowmobile. It’s a PSI 38/40 mm, the two numbers because the venturi is triangular. All the jets and such can be accessed from outside, useful for tuning in the pits.

The result is 50-plus blip, with redline raised from 7500 rpm to 8800, which is 1 ) close to a new Honda or Yamaha 450’s performance, and 2) about as much heat as an air-cooled two-stroke can tolerate for a two-minute heat or a four-minute main.

As for the modern part of the project, when Culver joined C&J he was tutored by co-founder Jeff Cole and learned the secrets; for instance, the optimum locations for the output sprocket and swingarm pivot.

C&J makes a variety of frames, with models for small two-strokes, vintage motocross, big four-stroke Singles and Twins, etc.

Each comes from a jig and fixtures. All Culver had to do was weld up a small flat-track frame, carefully measure where the CZ engine should be inside the loop, make the rear cradle and front plates and presto, vintage engine in modern frame, four bolts does it.

Suspension is equally state of the art, with Penske rear shock, fork from an early Yamaha R6, aftermarket rear brake, 19-inch rims and Goodyear dirt-track tires.

The C&J frame uses shared mounts, so the seat and tank came straight from 1 st Class Glass. (Why all the credits? Because Culver says everyone involved was so intrigued by the project that they all did more than they were paid for. The sum is more than the parts.)

What now? The CZ C&J weighs 205 pounds ready for the green Bag. In terms of power, weight, suspension and so forth, it specs out as a competitive Pro-class shorttracker.

Vintage racing is clearly out; no club in the world would allow something like this, replica frames and cad-cam engines not withstanding.

Richert will show the bike, parade it and maybe run a club race when the chance comes. The vintage/ modern hybrid won’t race in the Pro class.

But the fun is, it could.

Allan Girdler