Thumper Force

THUMPER FORCE

VERTEMATI’S FOUR-STROKE MOTOCROSSER IN SEARCH OF A WORLD TITLE

JIMMY LEWIS

VERTE-WHATI!?!? YOU'VE NEVER heard of the Vertemati MX bike, but if hard work and desire are any barometer, the lightweight four-stroke will be in the running for the 500cc world motocross title next year.

This is a rare piece—there are currently just six examples. Hand built in Italy, asking price $20,000 per, the bike is the brainchild of the Vertemati brothers, once the Husqvarna importers for Italy. When Cagiva purchased the Swedish company and moved it to Varese, the brothers were out of work. They turned to another Swedish make, Husaberg, fielding a motocross effort to promote the name. Slowly the bike they were racing became less and less Husaberg and more and more Vertemati until after a couple of seasons the brothers had their own bike, every piece differing from the Husaberg.

Enlisting the services of Californian tered.” A 38mm Dell'Orto carb with spot-on jetting helps immensely here, adds Young.

Mike Young, former Sound of Thunder Motocross Champion and sometime Cycle World test rider, the small Italian company set out to finish development and win some GPs. A second place in one moto in Italy and third overall at the Czech GP showed the bike’s potential.

Competing against 630cc Husabergs and Huskys, as well as the 500cc twostrokes, had the Vertematis searching for that ever-so-elusive balance between power and handling. Displacement ranged as high as 612cc before the current 497cc motor was finalized. Major surgery during the season included the replacement of the cam chain with gear drive. Most of the parts are made in-house at the Vertemati factory, a very small shop in Triuggio. Some of the gears and the crank are made by Folan in Sweden, but even these are hand-tailored before making their way onto the bike.

“You start the bike by kicking forward. like the old Honda ATC250,” explains Mike Young. “It's relatively simple once the forward kick is mas-

The hydraulic clutch pull is not as easy as expected, but it stays consistent throughout a 45-minute moto, Young says. It differs from the norm in that it routes hydraulic fluid through the cases to apply pressure on the clutch basket itself-no pushrod needed. The three-speed gearbox’s shift pattern is up-up-up, with neutral at the bottom. Motocross starts are about the only time first gear needs to be engaged. The power spread is so wide that on most tracks Young uses second gear only, third reserved for excessively long straights.

Want a horsepower figure? The Vertemati brothers are tight-lipped, but according to Young, who has ridden the fastest Husky, Honda and ATK racers, “It is like nothing we have in the States. It plain rips!” Young says the Vertemati will run neck and neck with any Open-class two-stroke and that its short-stroke motor gives away only a little in top-end horsepower to the larger works Thumpers on the circuit.

“It makes up for any lack of power in the tight turns, where its more-nimble handling comes into play. 1 rode it like a 125cc motocrosser, carrying speed through the turns and revving it.” says Young.

Gassed-up, the Vertemati weighs about 240 pounds-light for a Thumper but still no featherweight. Brembo brakes with special Action Shop pads squeezing Braking Honda-style rotors haul the bike down from speed. The brake lines are a special Kevlar tubing for reduced weight.

Young had trouble in the choppy exits of rutted turns, where all of the Thumpers suffered against the lighter two-strokes. But Young explains, “Put this bike on a slippery track and hooking up is what it’s all about. Just a little throttle control was all I needed to get launches out of turns that left the two-strokes and the huge fourstrokes spinning.”

The suspension is works WP front and rear, the shock activated through some of the trickest pieces ever spotted on a dirtbike. The linkage is all billet, as is the swingarm. It started life as a 90-pound chunk of 7075 aluminum and ended up a showpiece. The front fork is an upside-downer, its sliders coated with slippery titanium nitride.

More interesting is the design of the frame, which uses bolts in some highstress areas instead of welds. Very old school in thinking, this allowed a small amount of movement during severe

loading, which prevented other parts of the frame from breaking-bolts being more easily replaced than broken tubes. Similar to Husaberg’s design, the large, rectangular main-frame backbone doubles as an inlet that directs air into the carburetor.

The Vertemati brothers are hoping to produce a run of 15 machines, one at a time, most of which will end up in the hands of GP racers or collectors. How do you get one? Simple. Just bring $20,000 and get in line.