Tzf426 Strange Brew

TZF426 Strange Brew

NOT MUCH GOOD EVER came out of drinking beer, but the Yamaha roadracer shown here might be an exception.

“It all started with a 12-pack,” begins Ben Welch, owner, rider and co-builder of the so-called TZF426. “It was a few weeks after the September 11th attacks, and some friends and 1 were sitting around drinking and talking about how you couldn’t afford to put things off, because it could all end in an instant. The topic inevitably turned to motorcycles, and what our dream bikes would be. Flemming Tranberg suggested a 125cc Grand Prix roadracer powered by one of the new four-stroke motocross engines, and his idea sounded so good, I poached it!”

A motorcycle mechanic by trade, Welch recently opened his own shop, Speedskunk (www.speedskunk.com), the company logo a trio of skunk tails emulating the Legs of Man in honor of his entry in the 2000 Isle of Man Junior TT.

The idea for the TZF project couldn’t have come at a better time for Welch, because after a decade spent racing ever-faster motorcycles, the 34-year-old fatherto-be was scaling back his competitive activities. For a guy who got his start on a Yamaha SRX600, the notion of building the ultimate track Single proved impossible to resist.

And darn near impossible to build, too. After determining that the Yamaha YZ426F’s five-valve, dohc motor was the most roadrace-worthy of the MX Thumpers, Welch had a heck of a time finding one for sale. He ultimately bit the bullet and bought a brand-new 2002 YZ426F. Flis quest for a chassis didn’t go much better, as he ended up purchasing a complete used 1994 TZ 125, then had to buy a second chassis when the first one turned out to be cracked!

American FLYERS

Finally, it came time to join the two.

“1 knew I needed help for the next phase,” Welch continues, “and after a few conversations with people in San ego, one name came up several times: Rob North.”

Welch was familiar with the legendary Brit's work on 1970s BSA and Triumph Triple chassis, but didn’t know North now made his home in the West. So one morning before work, he packed his engine, chassis and résumé into his van and drove to North’s shop.

“Rob was interested, but cautious,” Welch recalls. “He told me to leave the parts with him, and when I returned two days later, he told me he didn’t think it

would work.”

Welch refused to take no for an answer, however, and eventually the pair came up with a workable plan.

To make the taller, wider YZ-F engine fit, North shaved the inside of the TZ frame spars and moved the radiator forward. He then fabricated an engine undercradle, an oil tank and an exhaust pipe that mimics the stock dimensions, but is routed differently.

Welch built the engine himself, initially installing a Crower cam and Keihin 41mm flat-slide carb that yielded 52 rear-wheel horsepower, up from the stock 47. Since these photos were taken, however, he's fabricated a fiberglass ram-airbox and installed a Wiseco 444cc piston kit that he figures are worth a few extra ponies.

Capping off the 192-pound creation is 2003 Honda RSI25 bodywork, chosen because the ’94 TZ fairing “was like a barn door.” Top speed is in the vicinity of 140 mph.

Early club-race outings at Sears Point and Willow' Springs confirmed that the TZF426 w'as competitive, as it smoked the Singlesclass competition. After that, though, things got complicated.

From the beginning, Welch’s goal was to com-

pete in the AMA Pro Thunder class, but he only did so once at Laguna Seca last summer before the class was eliminated. That left 250cc GP, but he barely had time to pre-enter this season’s California Speedway and Sears Point Nationals before the AMA announced that it was scrapping that class, too.

So, what’s next?

“I don’t really have any plans,” Welch laments. “I was thinking of going back to the Isle of Man for the centennial in 2007, but they dropped the Singles class.

I’d like to try to break the single-cylinder lap record at Willow' Springs-it’s a 1:27something and I’ve done a low 1:29 already. But lately I’ve been toying with the idea of putting a supercharger on it. That would be a wdld ride!”

You can almost hear the bottlecaps popping...

Brian Catterson