Cycle News - Archive Issues - 1980's

C'I 00 0") - ..... l-o 0. < (From top) The 250cc engine produces 62 hp at 11.800 rpm and weighs 66 lbs., four more than the 125. The 125's swingarm appears up to its demand and is made of super-light aircraft alloy. The 250'sleft profile. 28 .spa wned -S.D_ many imitators. There are now MBAs in almost every racing country in the world - including one in japan ! Half of the 450 or so customer bikes made since 1976 have been exported, with man y to France especially and the other European countries, a half dozen to Britain, two to Australia and a handful to the USA . It's certainly the most successful European production racer of the two-stroke era . In 1980 MBA expanded their horizons with the first machine to have been completely designed in-house - the 25Occ, penned by Giancarlo Cecchini, now with Sanvenero. Emilio Sanvenero was MBA's sponsor in Bianchi's championship year of 1980, but decided he wanted to build his own bikes, thus forming his own team to do so. The new 250cc convincingly won the Italian Championship with works rider Gianpaulo Marchetti, and a short run of 20 customer replicas were produced for 1981. These have, however, proved a great disappointment to all the unfortunate purchasers , some - such as South African Alan North - becoming so disillusioned with the bikes that they stopped even trying to use them after midseason. The trouble appears to have been insufficient development for privateer use, but this situation should be rectified for 1982, for none other than the " wiza rd of the two- stroke," jorg Moller , will be rejoining the team in 1982. Development of the 250cc will be his first priority: a new generation l25cc is also on the horizon for 1983. But for th e meantime the current 125cc has the measure of most of the rest of the co m petitio n, " Excep t for that superman Ni eto and h is Minarelli," grinned Dr. Ponsele as he showed me around the superbly equipped and spacious factory at San Angelo with his deputy, sales director SergioBoiani - how man y other racing bike manufacturers have or need a sales executive? From an original 35-37 bhp in 1976, th e customer bikes now produce 42-43 bhp at 14,200 rpm, with power from 10,500 making the bike relatively easy to ride compared to the ultra-narrow powerband tiddlers of even a very few years ago. How much better are the works bikes, I asked Sergio? "Only a little - they produce 44 bhp, but so me of our customers have made the same modifications and have actually beaten the factory bike on occasion, " was the answer. "We really wish there was another 125cc twin on the market, because then people could see what a real bargain an MBA is: we honestly do give our customers a bike that is in every way the nearest to our own works machine that it's possible to make it - and at a good price too (currently 8,799,000 lire for export about $7000). If Sanvenero really does carry out his promise to produce replicas of his machine, I doubt very much if they will be as well-priced or as competitive." The MBA 125 has achieved an excellent reputation for reliability, and the ability to be used almost straight out of the crate. "Indeed," said Sergio, "we're very proud of that - all our engines are tested on the brake before they're installed in the frame, and if they don't reach 42 bhp we rebuild them till they do. The other thing is that they simply don't wear out; many of our customers have been racing the same bike successfully now for three years or more, just updating it annually with ,the modified parts we can supply them with. The bike that Orsini won one of the European Championship rounds with is one of those - though actually his is four years old! To be truthful, that 's one reason our spares cost rather a lo t ....., we have to have them sitting on the shelf (MBA claim to supply any spare for either model by return) and since the bikes are almost too good and are so longlasting, we have to charge accordingly. That's one reason we decided to make the 250cc - we've achieved just about saturation of the European 125 market, anyway, and unlike say a TZ250 Yamaha, our customers don't have to buy a new bike each year. " Conversation with various European MBA owners appears to confirm this claim. The 125 MBA is a now-conven tional water-cooled parallel -twin two-stroke, with 28mm Mikuni carbs feeding 44 x 41mm cylinders through a pair of steel disc valves. Timing is 80°/210° on 125 and 250cc engines alike, with Nikasil coated cylinders and pistons both made by Mahle in German y. On the 250 the pistons have a 4 cm . thick graphite coating. One plain ring is fitted to each. There are six transfer and one exhaust port, with the cylinders included forward at 45°. The pressed-up crank runs in four ball bearings, with needle roller big and little ends.Thewhole assembly is made by Hoeckle, Crank life is exceptional for a highly-stressed 125ccrunning at 14,000 rpm: 1250 miles (2000 krn .). The cases are horizontally split, and bear a prancing horse emblem cast into the underside - they 're made for MBA by Ferrari in their new foundry at Maranello, and the famous car maker has also proved most helpful with advice, especially on the metallurgical front. In return, MBA were able to repay the favor when Ferrari designed and built an abortive two-stroke GP car a couple of years ago. The six-speed gearbox sits directly behind th e crank, and is made by CMA in Bologna, feeding through a six-spring clutch with six friction and five steel plates. Unfortunately, you have to split the cases on the 125cc to change the internal ratios, whereas the more recent 250cc has its crankcase cast in three pieces to permit internal gears to be changed without even removing the engine from the fram e. Customers can specify either right or left shift lever surprisingly, perhaps, the ratio is about 50/50 - so much for japanese standardization! There is a choiceof three different ratios for each gear. Ignition is by twin battery-powered Krober units mounted behind the revcouruer from the same manufacturer. The mechanical water-pump is driven off the primary side of the geabox. The entire engine package, with gearbox oil but no water, weighs 621bs. The 250cc engine has a similar specification except as detailed above, but has 55 x 52mm cylinders for a capacity of 247cc.Output is 62 bhp at 11,800 rpm, with power from 6,000 rpm supposedly, though speaking to a couple of the owners the true powerband is nowhere near that wide. Mikuni 34mm carbs are fitted, and the engine unit weighs only four pounds more than the 125 at 66 pounds thanks to the extensive useof magnesium - only the main crankcase casting is in alloy. . Hidden behind a mocked-up fairing during my 'visit was a 125cc engine with reversed cylinders and rear-facing exhaust pons. Ap parently revving to 15,500 rpm, this prototype produces much better torque as well, but the company have since decided not to persevere with it for the tim~ being as the power tails off at peak revs. Doubtless one of jorg Moller's first priorities will be to take a closer look at this design, since as he told me on my visit to Ad Maiora, he's a believer in rear-facing exhausts. • ... •• I •• , ..

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