“Roadracing World” Feb.1999
Planned For Daytona
By Michael D. Green
In one area of the pits, a large Italian commanded a team of six silver and red motorcycles and four American riders. The vociferous Italian was Primo Zanzani, and he was at Daytona to supervise the efforts of the factory-backed U.S. Motobi team. This was a day they would all remember.
Motobi and Benelli originated from the same family, literally. The Benelli brothers-Giuseppe, Giovanni, Francesco, Filippo, Domenico, and Antonio-founded BeneIli in 1911 and earned their living in Pesaro, on ltaly’s picturesque Adriatic coast. At first they did odd mechanical jobs and repaired guns, cars, and motorcycles, but in 1919 the brothers strapped a 98cc two-stroke motor onto the back of a bicycle and called themselves motorcycle manufacturers. In 1927 they produced their first four-stroke-a 175cc Single, with a gear-driven DOHC motor and it quickly found its way onto Italian race tracks…>
<The old two-strokes were abandoned, and Motobi focused all its production on the four-stroke Single. Giuseppe Benelli died in 1957, leaving Luigi and Marco to run the factory. The brothers’ first move was to hire a new tuner for the race department, a 34- year- oId former racer from Northern Italy named Primo Zanzani. Zanzani had been tuning his own machinery since the end of the war and quickly went to work extracting more power from the Motobi Single. lt was a painstaking task that took him most of the next 10 years. Back in America, the sale of small motorcycles was also starting to skyrocket. Motobis were imported by Boston’s John and Deano Berti, owners of Cycle Products of USA, Inc.. Like their Italian counterparts, they believed that the best way to advertise their product was through success on the racetrack, and they decided to mount a major effort for the 1962 USMC race at Daytona. Four 207s and two 125s were shipped from Pesaro to Boston, and Zanzani flew in to oversee their preparation. Jess Thomas was the team’s lead rider. Thomas was from Fort Worth, Texas, but he spent most of 1960 and 1961 racing on the East Coast in the new, but vibrant, road racing scene. Thomas was sponsored by Don Wiegle, the New Jersey based NSU importer, and won a lot of races on an NSU Supermax. Thomas planned to race the NSU at Daytona, but was also offered a ride on the Motobi team; he planned to test the 207 and then decide which bike to ride. ” It took two laps on the Motobi to make up my mind,” recalls Thomas, 37 years later. ” It was so light and nimble, and the Oldanis gave it incredible braking power. It was the first real works machine I had ridden, and I knew it was something special”. The Motobis were far removed from their street bike roots, and the dark sandcast motors were the most obvious change. The plain bearing at the bottom end was replaced by rollers, and the 4-speed transmission ran on needle bearings. The magneto was replaced with a battery… >
<Thomas’ competition at Daytona was serious-Kunimitsu Takahashi and Giichi Suzuki on the factory Hondas. Honda had been racing outside Japan for only three years. But after leaving Daytona, the 250cc four-cylinder RC162 won every Grand Prix, except for the final round in Argentina, which Honda did not contest. The 125cc twin-cylinder RC 145 did the same, with Takahashi himself winning the first two rounds. True to form, the two Hondas dominated Saturday’s 100-kilometer 125cc race. Takahashi and Suzuki finished two laps ahead of Thomas. Jim McMurren followed on a second Zanzani tuned Motobi. McMurren, a dirt tracker from California, was afraid that the AMA would revoke his license for riding in the USMC race and rode at Daytona under the alias of Jim Kellog. Sunday’s 125-kilometer 250cc race was a different story. Only the 500s used Daytona’s banking-the 50cc, 125cc, and 250cc fields ran on a 1.66-mile infield course. The 40-horsepower Hondas were just too big and unwieldy for the light layout, and Thomas nipped at their heels lap-after-lap on the 26-horsepower Motobi. Takahashi and Suzuki would rocket down the short straights only to be caught by Thomas in the corners. “The Hondas could barely stay on the track and kept running wide, “smiled Thomas, as he recalled that remarkable day. “Plus they had a really steep power curve that was hard to manage. I had much better brakes and could run up on them in every turn. Finally I got too embarrassing for the Honda management to watch and they pulled their riders in.
Takahashi led from the start but pulled in after 11 of 46 laps: Suzuki was on pit road five lap later. McMurren retired on lap 18 , and Thomas was left to romp to victory, a lap ahead of the Ducati of Jim Hayes. Bill Powers was fourth on another Zanzani Motobi: Abbott Lahti crashed his on lap 10. “The Motobi was very fragile”, remembered Thomas, “and Zanzani was waving at me through the infield to try and slow me down at the end of the race. It was the first time I’d ever been directed during a race event. He stayed on for one more event in the U.S.: he was forceful and hard-headed, but he taught me an enormous amount. “He showed me how to maintain the motor-I remember there were special tools for measuring the cam timing and adjusting the valves. The inlet valve were paper thin and had to be replaced after a couple of race weekends.
But the bikes were incredible, everything was hand done. In typical Italian style you could see hundreds of man hours had been invested. I kept the 207 Motobi and won 26 races on it during the 1962 season. I was racing at tracks from Mosport, Canada, to airport circuits in Texas-every race I could get to!”
During 1962 the Motobi factory, moved back under the wing of Benelli, now run by Giovanni Benelli. Zanzani moved over to the Benelli race shop, where he helped develop the 250cc four-cylinder, being ridden by Tarqinio Provini. Zanzani was one of the first race engineers to recognize the advantages of disc brakes and fitted them to Provinì’s race bikes for the 1965 season. The brakes weren’t Italian but were modified from a go-kart application by Bo Gehring in his MotoTEC shop in Harpers Ferry, West Virginia.
All was not well in the Beneili race shop, however, Zanzani butted heads with Giovanni Benelli, and in 1966 he moved back to the Motobi factory to continue his work on the 250cc Single. The four studs that held the cylinder head in place were arranged In a rectangular rather than a square, and Zanzani found that he could not raise the compression and maintain a seal between the head and cylinder: his answer was the six-tiranti or six-stud head, which withstood a 10:1 compression ratio. The modified motor also included a stronger crankshaft, a new cam and rocker arm design, bigger sodium-filled valves set at a 10-degree-steeper angle, stronger sand-cast cases, and a larger carburetor. The end result was 36 horsepower at 10,500 rpm, six more than the best four stud motor and more than double the output from the street motor. Zanzani also recognized the importance of keeping weight to a minimum, and his new race bike weighed just 205 pounds, 40 less than the street bike.
Zanzani returned to Daytona in 1967 with Italian Silvano Bertarelli and his new motorcycle. Bertarelli ran into licensing problems with the AMA and entered the 78-mile Novice race as Sam Bertoral from Philadelphia. But Zanzani’s return trip was not a repeat of his heroic triumph five years earlier…>
<It was no coincidence that Bertarelli listed Philadelphia as his home town. Cosmopolitan Motors in Philadelphia took over the Benelli franchise from CycIe Products of USA in 1965, and Cosmo imported the 250cc Barracuda and the 125cc and 200cc Sprite models until the end of the decade; in the U.S. the bikes had Benelli stickers on the tank, but in Europe they were sold as Motobi. The five speed 250cc Super Sport appeared later; the motor was fitted with a new camshaft, and its longer connecting rod resulted in a lightly different engine shape.>
<… and in 1967 Wise brought over a second Italian to provide technical support for their Benelli dealers. Eraldo Ferracci came straight out of Zanzani’s race shop in Pesaro and worked for Cosmo for almost 10 years before moving to a local Honda dealership.
Zanzani was long gone at this point. He left Motobi when the race shop closed but continued te work on Motobi racebikes in his own shop in Pesaro. His jewel was still the ‘six tiranti’, and 15 bikes with six-stud motors were built in the next two years, four of which were shipped to the U.S.. Zanzani returned to disc brake technology and developed a method to spray aluminum disc rotors with iron, thus producing a light-but-tough rotor. Zanzani’s rotors won 24 World Championships in the 50cc, 80cc, 125cc, and 250cc classes between 1978 and 1989. Zanzani’s final World Championship came with Alessandro Gramigni on the 125cc Aprilia in 1992.
Today, Zanzani and his sons Athos and Mirko run three large machining facilities in Pesaro, producing multiple-spindle boring units for woodworking machinery. Behind the scene, Zanzani s.r.l. still makes disc rotors and Motobi spare parts, and it was only natural that the company decided to start building replica of the six-tiranti. The firm had the machining resources and access to stockpiles of NOS Motobi parts, from both Pesaro and Philadelphia. A dose of ltalian passion fueled the decision to introduce Motobi to the world of vintage road racing…>