'ROADRACING WORLD' FEB 1999The story:
BY MICHAEL D.GREEN:
<...The Benelli brothers' first move was to hire a new tuner for the race department, a 34-year-old 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...><... He left Motobi when the race shop closed but continued to 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 Primo & C. SNC still makes disc rotors and Motobi spare parts, and it was only natural that the company decided to start building replicas of the six-tiranti... A dose of ltalian passion fueled the decision to introduce Motobi to the world of vintage road racing…>
'CLASSIC RACERS'
SEPT.-OCT 1999
BY ALAN CATHCART
<..A self-taught tuner, Zanzani was the man responsible for turning the four-stroke family of Motobi models into such competitive hardware both in Italy and the USA. This success earned him the task of developing the four-cylinder Benelli 250 GP racer from 1962 onwards, when the two companies were united. Having turned it into a Grand Prix race-winner in the hands of Tarquinio Provini, Zanzani moved back to Motobi in 1966. There he focused his attention on the new 250cc Sprite model introduced that year, with the specific purpose of making it a winner in the recently-introduced quarter-litre MSDS class for customers of the Pesaro factory. The fact that Motobi won the Italian 250cc Junior title in 1966, '67 and '69 shows how well Zanzani succeeded. But by the end of the decade, competition was so intense from rival factories like Ducati, Parilla, Aermacchi and Morini that he had been forced to develop a limited edition homologation special known as the 'Sei Tiranti' (six-stud).Produced in very limited quantities this had six cylinder head studs instead of the street Sprite's four, a factor which caused problems with cylinder head sealing when compression and engine speeds were raised in pursuit of power. Considering that by the end of the decade Zanzani had doubled the 16bhp output of the street 250 to 33bhp in MSDS form, this was hardly surprising. So an extra pair of studs was grafted in to bolt the cylinder head to what on this tricked-out special were sand-cast crankcases for extra stiffness, rather than the diecast ones of the street bike. Make no mistake, this was for a silhouette c!ass, where every little trick was employed to gain an added edge. Bit like Supersport racing today, really....Imagine if Colin Seeley himself were to restart construction today of his 7R/G50-powered racebikes. Same deal...
...In parallel with this, Zanzani developed a specialist expertise in the disc brake technology then new to motorcycles. He'd been the first in the world to adopt them on a GP racer back in 1965 on the four-cylinder Benelli, using US made Airheart discs rather than the cable operated Campagnolo brakes produced in ltaly for lightweight machines.
Zanzani developed his own process for plasma spraying aluminium disc rotors with iron to produce a far lighter disc brake package than the steel or cast iron discs then commercially available. These discs offered notable benefits in terms of reducing unsprung weight and gyroscopic effect. His brakes became ubiquitous components on GP racers in the smaller classes, winning no less than 24 world championships in the 50/80/125/250cc classes from 1978 onwards, up to and including Alessandro Gramigni 's 125 Aprilia World crown in 1992.
Today with his two sons at the age of 77, Primo Zanzani concentrates on running the trio of high-tech machine shops his family owns in Pesaro, producing intricate components for the local woodworking machinery industry - and Motobi 250 Sei Tiranti replicas!>