Cycle News - Archive Issues - 1990's

RACERTEsr Pami·BMW F650 (Above left) The Paml-BMW's excellent frame and extreme forward weight bias combine to make a bike that thrives on high corner speeds - the key to success In singles racing - and even good for trying to pass 916s mldcorner. (Above) Gottfried Michels is the coordinator of the seven-member Pami racing consortium. The group first concentrated on motocross racing in 1975, then switched to road racing In 1985. By Alan Cathcart Photos by Kel Edge t was {he classic David and Goliath battle. Only this time, might beat right. For 50 miles of the BEARS World Series round on a rain-lashed Thruxton circuit, Mike "Spike" Edwards on the little Pami-BMW single had led the race, holding Daytona winner Andrew Stroud's powerful Britten V-twin at bay even once they started lapping slower riders, the two of them pulling inexorably away from a field of fleet four' strokes headed by yours truly on the Saxon Triumph triple and Paul Lewis' Raceco Guzzi. A fairy-tale result was m. the cards. A great little'un had the beating of a fleet of faster big'uns. Only it wasn't to be. On the very last comer of the race, with the checkered flag in sight, Spike the Bike got hung up with a backmarker, and Britten-mounted Stroud pounced, grabbing the lead for the first time and 'outpowering the little German single to the line. Not in·the classic script. Still, even by finishing second, the Pami team had proven how c.ompetitive their Tigcraft-framed, BMW-F650engined racer had become on the world stage. This fact was underlined at Assen in August, when Edwards outquaHfied 84 of the top Sound of Singles racers in the world - including German champion Tommy Korner on his all-conquering GDM-Rotax - to grab pole position for the race that has become the unofficial world championship of the Supermono class. But a practice spill - caused by a set of crankcases that finally cracked after more than 3000 miles of race and .dyno time - resulted in a rebuilt bike that handled strangely, leaving Edwards just three seconds behind Korner at the end of the race. But, for the German Pami team - a (J 26 cooperative of seven friends from various walks of life based in Trier, capital of the Mosel wine country - due consolation came a few weeks later when regular rider Herbert Enzinger clinched the German SOS Championship by winning the final round at Dahlem, wresting the title from the GDM-Rotax team whose bikes have dominated the series for the past three years. In a season when Enzinger won two rounds and placed second and third twice each in the German series, as well as finishing third behind Komer and me at Daytona, the Pami team had turned the new BMW engine into a serious contender for Supermono supremacy - in spite of its humble Funduro heritage. Coordinator of the Pami racing consortium is 40-year-old Gottfried Michels, a CNC design engineer heading up the cooperative of seven like-minded enthusiasts whose hobby since 1975 has been racing together - first in the motocross world, then from 1985 in road racing.. Initially, Pami campaigned Yamaha, SR-powered specials of their own construction, the most recent of which was a tricked-out, Tigcraft-framed racer with Pami's own DOHC cylinder head machined from the solid, which has now ended up in Japan where it regularly wins two-valve SoS races. The bike was sold to fund construction of a contender for outright Supermono victory. One would think that with aU their SR experience, an XTZ Yamaha five-valver might have been favored, but Michels says they considered but rejected it. "Ducati showed you must have plain bearings and a strong crankcase design, and the Yamaha has neither," he says. "But when the BMW Funduro was announced, we saw it had what we needed - plus the engine was made by Rotax, which is a good guarantee of four-stroke excellence. And it was German!" Though BMW has failed to offer any concrete support beyond helpful advice, says Michels, Rotax has backed the Pami project enthusiastically. It's worth underlining, though, that transforming the Funduro into a title-winner has been largely the self-funded consortium's own work, making the level of their achievement without any major sponsor all the more creditable. 'Originally based on the stock BMW engine's 83mm stroke, the Pami finished second to Korner in its racing debut in '94 before being converted to shortstroke specification with the team's own 'eccentric-pin crank. Pami's high-tech machine shop allows them to fabricate practially any one-off engine part, from laser-cut CNC head gaskets to their own valves and even cylinders and heads. So the 105 x 80mm engine which Enzinger debuted at Daytona in '95 and went on to win the German title with Pami's own special cylinder with a chrome Nikasil bore, and a two-ring slipper piston they m'achined themselves from an Asso blank, fitted to a Carrillo rod 4mm shorter than standard and delivering 11.5:1 compression. Pami also made its own five-speed close-ratio gearbox, cutting the teeth themselves (though Rotax took care of heat treating the result), mated to a stock oil-bath clutch with up-rated springs. The crankcases are modified to carry less oil, with the dry-sw;np, 3-liter oil tank integrated into the frame behind the steering head. In addition, Pami has developed its own programmable digital ignition with a choice of half a dozen different curves for each EPROM chip, but nas so far resisted going to fuelinjection, preferring to rely on a pair 6f surprisingly small 36mm flat-slide Mikunis for the time being. "Eighty percent of our tuning effort has gone into the cylinder head; that's where the real power is hidden," says Gottfried Michels, citing Pami's Luxem.bourg associate Raymond Derrman as the man mainly responsible for waving his magic wand over the four-valve, chain-driven DOHC top end. Derrman is a noted tuner of BMW car engines, and the F650 motor has much in common with its four-wheeled ·brethren. "The cylinder head, crank bearings, pin size, 40-degree, valve angle, valve timing, 'bucket camshafts all these are trademark BMW design ,features," says Michels, "so there's strong potential for crossover tuning expertise." So Pami machines its own cam profiles on cast-iron blanks supplied by Rotax, increases the squish area, flows and ports the head, fits its own guides, shims and so forth to the oversize valves made in-house, the sizes . of which are increased 3mm from. stock to 39mm inlets/36mm exhausts. The end result is impressive dyno figures that have been corroborated by independent tests: 85 bhp at the crank at 8600 rpm in '694cc short-stroke form. Gottfried Michels says there's more to come. "I think 700cc is an ideal capacity, but shortening the stroke further to 75mm and using a 108mm or even 110mm bore would be better still," he says. "A bigger bore would prevent the hot spot you get on one side with such big valves, and the shorter stroke will allow higher rpm and so more power. The BMW engine is very robust, so the crankcases can stand it." Pami plans to help fund their future racing activities by building five replicas of Enzinger's title-winning bike, but incorporating some of these ideas, in addiMh to the tuning parts they already supply to other BMW users like Dave Morris and Tigcraft itself in England. But that's the future. What's already here and now is impressive enough. Using a Tigcraft twin-spar alloy chassis with carbon-fiber subframe for the

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