Cycle News - Archive Issues - 1970's

/ ~ w z W ...J o >o Glen Kyle always has been somewhat eccentric to the traditions that have grown up around the very specialized sport of Class Jlr hillclimbing. For example, against the tried and true Indians and Harley-Davidsons, he has campaigned a Vincent for several years, choosing to follow his own thinking in motor design. The net result has been three National Championships, in 1963, 1965, and 1966. And since Glen injured his wrist and sold the Vincent to 1969 National Champion Beese Wendt in 1967, the machine has taken one more AMA Championship and a Canadian National Championship, further proving the soundness of his technical leanings. TEXT AND PHOTOS BY ED YOUNGBLOOD Kyle, an extraordinary machinist from Goshen, Indiana, and father of three, found himself too busy to ride when he recovered from his injuries. Instead, he had taken up flying and was considering doing it commercially. However, when he de.cided it wiser to stay with his established profession, he realized that flying as a mere hobby was not satisfactory for him. It was too time-consuming and too expensive. Glen began to miss the hills and the noise of the Class A fuelers. A general idea for his new hillclimbing special had been forming in his mind for several years now, and in 1969 he began to lay plans with a new motor he had never seen the insides of. It was a cammer, and that is all he cared about. Theoretically, it was what he wanted, and the practical problems would just have to be worked out in the shop. The following is the story of his revolutionary, fuel-burning, overhead earn hillclimber. ' Long before Glen Kyle injured his wrist, turned his Vincent over to Beese- Wendt, then sold it to him in 1967, he had been thinking of an overhead cam Oass A hillclimber. The dream was a logical conclusion of the direction his engineeriJ:lg theories had taken during his career as a professional rider. Kyle cOn<;entrates on the breathing efficiency of the internal combustion .,ngine. Beciuse the runs for a hillclimber are relatively short, such a special machine has needs similar to tho"" of a dragster. Within reasonable limits, one doesn't worry about heat and piston speed. Tremendous h?rsepower in one place and at one time is needed, so attention should be directed to the greatest volumetric efficiency over short periods of time. The motor must inhale and exhale great gulps of gas and air as rapidly .as possible. Achieving this goal had led Kyle down what seems to be a strange road with the successful Vincent. The fmal result was a motor that reversed the major rules that most racing engines follow. For example, with a track racer the tuner DeUortos wlth ......lItIl float bowl. meet the Eagle'. fuel and . , need•• Length of lIIIIocity tube is determined methemeticelly. The Ie_n supplies the bere minimum of ei,-cleening. Right is e stock nlve. Compue it wlth the rep'-ment ...... on the left. It begen _ e Clltlwl'oIlIt pert. frequently bores out a slightly smaller motor in an effort to increase the volume while keeping the stroke and thus the amount of piston travel the same. With the hillclimbing Vincent, though, Kyle took the opposite approach. He began with a lOOOcc machine and sleeved it down to 75Occ. This gave him a motor that would conform to the AMA motor limit for overhead valve Class A hillclimbers, and it gave him i motor with a long stroke and oversized combustion chambers. With the lOOOcc Vincent heads he had room for valves that were very large in comparison to wbat he could get into any other 750cc engine. A great amount ofplston travel didn't matter. The runs are short and overheating and seizure are unlikely if lubrication is adeq uate.· So through the small-bore Vincent with its large valves and oversized combustion chambers, Kyle achieved the volumetric efficiency he wanted for his Oass A bike. However, mechanical efficiency, he felt, was limited by the design of the- pushrod motor. An overhead cam machine would have less reciprocating weight and therefore a higher rate of acceleration, but such a mechani"'" was not available on any suitably large motor. Glen at first toyed with the idea of grafting 450cc Ducati heads to the Vincent cylinders. It was a makeshift scheme based on necessity rather than desirability, for nothing else was available. Mounting problems would have to be solved, then driveshafts would have to be fabricated and moun ted to transfer the power from the Vincent's camshafts to the Ducati heads. It sounds impossible, but, aftera!!, Kyle had fabricated many of the parts for the Vincent, including the pistons. But then the three-times National Champion cracked his wrist, sold his Vincent, and went into a brief retirement. During this period, at least two desirable motors became available, and, fortunately, when Kyle returned to professional competition, he could shelve the idea of the overly difficult Ducati-V"mcent marriage. At first the Honda Four was considered. Lt had the overhead cam design Kyle wanted, and it was the proper size, but it also was heavy, and the multiplicity of cylinders would cause tuning problems. For best results, one wants to plug one carb into each cylinder, so with more cylinders come more problems with carburetor syncronization. Besides, Glen couldn't seem to interest anyone at Honda m the possibility of having a Honda National Hillclimbing Champion, and he wasn't about to invest around $1500 in a road bike and pull out its motor for experimentation. In the meantime, Jim Snell of Snell's Cycle in Muskegon, Michigan, suggested the '/5Ucc Laverda cammer that was being marketed by Jack McCormack as the top of the American Eagle line. Kyle liked the idea of an overhead cam twin, so Snell entered a formal request with McCormack International for a motor. Apparently Jack McCormack liked the idea also, for in the spring of 1970 a nearly complete engine arrived in a crate. It was a used motor taken from a street machine on the west coast. It lacked the electric starter, and nothing else from the bike was included. But Glen Kyle had all he needed.' Immediately he took the motor to his home machine shop and pulled it down. It looked clean. Cylinders, cams, pistons, and valves showed little wear. And to his greater pleasure, Kyle discovered that the machine he chose on a hunch was in fact a tuner's delight. He had gotten it only for its carnmed heads and its availability, but inside he discovered features of design that held promise of a superlative competition engine. First, there is a very hefty and very sufficiently mounted crankshaft. In all there are five bearings; balls hold the shaft in the

• Cover