Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/126498
o 00 0') at the powerplant. Each engine is connected by belts to an overhead jackshaft. Belts near the rear bulkhead connect the jackshaft to 'an industrial gearbox. (Right) Aluminum rear wheel, notched for traction and riding on a monoshock swingarm, is driven by twin belts. (Left) Vesco and his father look Z1300 'liner ready for '81 the y~ars, belt-changing was a frequent exerCise. He also had problems with gear breakage with the KZlOOOs, with his traditional system of using the gearbox of only one engine. The different drive system of the new 'liner designed around the two .massive KZ1300 engines and using both transmissions looks bullet-proof. Each en,pne feeds a belt which ascends to an overhead jackshaft. Another belt takes the power down to a rectangular black industrial gearbox located under the rear bulkhead, where it.is changed from latitudinal to longitudinal in direction. Twin belts run from this final transmission to either side of the rear hub. All the pulleys and all the Uniroyal belts are of an impressively large size. The pulley at the rear center of each engine bolts nicely to a four-bolt flange, stock in the driveshaft system of the original motorcycle. The KZI300 has a stout clutch, further augmented in this case by heavy-duty springs. To save Don's hand, the dutch is activated by the nitrogen system also serving the skids, the Murdock air shifter (like those used on drag bikes), and the low and high speed parachute releases. Besides the clutch springs, there are only three changes to the stock engines. These are: heavy-duty valve springs, 6-to-l turbo pistons, and turbo cams. The cams are an example of Don's supplier problems. They had billets off of the Kaw assembly line, but they were not heat-treated. The original cam grinder Don contacted couldn't handle this. At the last minute, Don found thar Bob Dunlavy, a fellow Salt Flat~ rider who specializes in racing cams, could provide a solution. Bob took stock cams, face-welded and reground them, a time-consuming job not suited to the higher volume operation of the original supplier. The Dunlavy cams were finished only days before the group arrived at the salt. Don's system is to go up through the gears, and then flip the boost control switch until he gets the boost pressure he wants. The plan is to use two atmospheres, or 30 lb. of boost. One of his previous problems was a boost control that wouldn't maintain the pressure; on this year's control a bigger motor is used. Stock electronic ignition was retained. Another kind was an order because they didn't know if the stock system would do the job, but the replacement didn't arrive. With a few small modifications, the stock system appears to be adequate. For the higher speeds, a strong, new method of frame and body construction is used for the cockpit and engine compartments. An aluminum "tub" built like an aircraft wing was fabricated by Rob North, fonning the whole of the cockpit, except for the 30 lb. roll cage around Don's head and upper body, itself securely joined to the tub with 80 rivets. Five of the tub's facets are continued back into the lower part of the engine compartment. The upper part of the engine compartment is of the usual steel tubing, as are the front and rear compartments containing the wheels and other parts. The tub is covered with foam to round it on the exterior, and then fiberglass. Another source of delay - the fire marshal descended upon the shop during one of the last days, after com-plaints by the neighbors about the fiberglassing. Thereafter, they had to work at night, undetected but slowed in their progress. Only a warrant in hand stops Don. At the very front are the nitrogen bottles and the handsome, transparent stock KZ1300 batteries. One is only for the total loss ignition system, the other for everything else. Everything possible is activated by electric solenoids at the spot, saving a whole tangle of cables running through the compartments. Starting is by two external car batteries applied to a built-in starter motor, a source of trouble on the cold day at the salt. The bike had been started easily in the shop where it was warm, and without the additional drag of the rear wheel since it was not yet attached. Though starting plugs are used (N9s, which are the ones specified for the KZ1300 street bike), methanol is cold fuel anyway, the low 6-to-l compression does not heat it up much, and the jumper cables they picked up did not flow sufficient electricity to turn the engines fast enough. They did start, but it took a while, after plugs became fouled and were changed. Cooler N657 plugs are used when racing. The bike has an exciting, powerful roar, but due to the water jackets and the muffling of the turbo mounted between the engines not the annoying scream of most race engines. The same AiResearch turbo unit is used as in the old 'liner, being in the right size range for both, largish for the old 'liner and smallish for the new one but adequate for both. Tires are a continuing problem for the fastest of Salt Flats racers. Tire companies are no longer interested in making Bonneville tires. Don was only able to run the old 'liner, at the last, because of the kind donation of a hoard of Bonneville tires by the sponsors of a former LSR 'liner. So he went to all-aluminum wheels. The combination rim/tire ring is one piece of forged and machined 70-75 T6 aluminum, one of the hardest alloys. The hub is similar to that of a standard motorcycle design, except that the axle is treated to an oil bath instead of a grease job. Oil will stay cooler than grease, and is held in by seals so it can't fling out. The aluminum discs used in place of spokes are not flat, as they appear to be at first glance, but were spun by Jackman Wheels, a process which shapes them something like turning on a lathe, except they are bent by the tools instead of cut. The two discs are close together and parallel to each other at the rim, then angled out towards the edge ,?f the hub, then bent again at right angles to the hub for fastening at their centers. The rear wheel is huge, like the big wheels used on LSR cars 20 years and more ago, before small wheels became available. It has large Xs engraved onto the weight-bearing surface for traction, chamfered to self-clean. The crew was gratified on Tuesday's short run that the Xs cut sharp marks into the mushy salt, indicating that they were working and providing traction. The Hilborn fuel injection system sends more than enough fuel to the engines, about twice as much, through a large line. running from the bottom of the eight-gallon tank. (The bike uses 2!-! gallons of methanol a minute on a run.) A boost compensator mounted on the top front edge of the tank monitors the manifold pressure and regulates the return of surplus fuel from the engines through a much smaller line, by means of a diaphragm and needle valve, allowing a range of pressure and volume in the return line. This feedback is necessary when using a Hilborn system with a turbocharger. Unlike positive displacement blowers, turbochargers do not always use the same amount of fuel at a given engine speed. The turbocharger has a separate oil pump. If an engine should break, the turbocharger will not get pieces of metal in it from a common oil supply. Race car technology is borrowed whenever appropriate, as in the huge Hurst rear brake caliper. The burly monoshocks front and rear are also car-sized. The new bike worked out remarkably well for all the hassles and innovations; the shock springs appeared to be the main boo-boo. Spring rate for the big shocks was figured for the estimated l400-lb. weight of the bike, but the crew found on the salt Tuesday when the bike touched the ground for only the second time that the spring was about half as stiff as it ought to be. Perhaps somewhere along the line, someone was thinking of a pair of shocks instead of monoshocks. The crew did a modifica tion as best they could so Don could run. The new 'liner, except for a few minor details (like shock springs and canopy vent holes) is all ready for a full season next year. 1981 promises to be a memorable year in the history of motorcycle speed trials. Don's goal, as it is well known, is to surpass the Summers brothers wheel-driven car record of 409 mph, set, ironically enough, Nov. 12, 1965. He estimates that the bike will go 425, 435, or even 450. The Jammer group is improving their mount every year, and while their probabilities are lower, with a reworked vehicle like Don's old one instead of a fresh design, they have a good chance for some very fast times. It may turn out to be an exciting horse race, even more so if any of the car guys get the money together for a wheel-driven LSR effort. • 7