American Eagle 750 Super Sport
AMERICAN EAGLE 750 SUPER SPORT
A Refreshingly Nimble Heavyweight Sure To Please The Connoisseur
THE AMERICAN EAGLE 750 is a brawny machine with excellent road manners. Better yet, burly but graceful.
Too easily, it could have turned out a lumbering leviathan, because with big bikes, comfort and accessories too often take precedence over sanity of design. Fortunately, the Eagle's builder, Laverda of Italy, has wisely avoided this pitfall, comfortably blending form with function. The result is a man-sized machine weighing almost 500 lb. that somehow moves very nimbly. To our mind, this is one of the best heavyweight tourers available.
We base this judgment on several factors, not the least of which is quality. The castings used in the engine and transmission are among the best we've ever seen on a production machine. All of the cast alloy pieces from the crankcase up are excellent, being completely devoid of flash, flaws or surface irregularities. They are also admirably beefy in all the appropriate places; bearing webs are thick while unstressed areas are trim.
To ease accessibility to the big fellow's innards, the crankcase halves mate horizontally rather than vertically. So for a complete clutch, bottom end and gearbox inspection, the engine is dropped from the frame, turned upside down and the bottom crankcase half removed, exposing all the gears, shafts, etc. And although this practice of horizontally split cases is becoming more common in lightweight machines, it is still relatively rare in big bore engines. However, as time passes this may well become universal procedure, easing maintenance of bikes of the future to a great degree.
A team of four main bearings supports the crankshaft assembly, two caged rollers and two ball bearings. These provide the strength needed for reliability at high rpm. And even though power begins to drop away quickly above 7200 rpm, the engine is redlined at 8500 rpm, leaving a comfortable margin for rider error. We might also point out that even at this upper limit of engine revolutions the Eagle's mean piston speed is only a hair over 4000 ft./min., a generally accepted maximum figure for high speed reliability.
Appropriately also, the connecting rods are made of I-section steel which is generously hefty in all stressed areas. Roller bearings carry the big ends of the rods while bronze bushings take care of wrist pin loadings.
That venerable Italian firm, Mondial, makes the three-ring pistons, utilizing a low-expansion aluminum alloy. The top compression ring is chrome plated, as is the oil control piston ring. But the factory has opted not to chrome the second compression ring, rather a softer and better sealing cast iron ring is fitted. This follows conventional automotive practice where the premium is placed on longer life with lesser maintenance. Significant, too, is that the oil ring has a spring expander fitter behind it to keep constant pressure against the cylinder wall for maximum oil control.
While the engine is basically the same as previous models, it has been hotrodded slightly to increase performance with no apparent strain or irascibility. Compression was bumped up from 7.7:1 to 9.6:1 by means of domed pistons. Also, 30-mm square slide Dellorto carburetors are fitted in place of last year's 29-mm units. And to take better advantage of these
improvements a sport profde camshaft with a bit hairier timing and lift is included in the package.
Adding to the machine's long life is a centrifugal oil filter which services the common oil supply for the engine and transmission. A gear type oil pump forces the lubricant into the filter which spins heavier impurities out into an outer housing. This filter is accessible inside the primary chaincase cover. There is also a screen at the bottom of the oil sump that catches particles of fung before they are drawn up into the pump.
Furthermore, as the American Eagle's wet sump oil system effectively eliminates external oil lines and fittings, unsightly leaks and oozes are done away with, contributing greatly to the bike's external cleanliness.
In the transmission things follow a more or less conventional pattern; both mainshaft and countershaft are supported by ball bearings at either end and the gears are adequately chunky. The unit's outstanding feature, however, is the shifting drum. This is unique in that clever design has cut its weight in half.
An overly heavy shifting drum, when actuated by the toe lever, will often override its detent mechanism if moved too quickly, and engage an unwanted neutral or skip a gear. Surprisingly, this quirk is present in numerous modern motorcycles. Consequently, it is common practice of many racers to lighten the shifting mechanisms in their bikes to achieve positive, reliable gearchange response.
Laverda's approach to this problem has been to use an aluminum casting sheathed with steel rather than using steel
throughout. So while the mass of the unit is light alloy, only the portion of the drum subject to wear—the part which contacts the shifting forks—is made of harder, heavier steel. The efficiency of this design becomes quite obvious when you cake a couple of hard, quick trips through the gears, as we did at the drag strip. Each shift was light and sure, with or without the clutch.
T he Eagle's electrics draw current from a 12-V battery and generator system. But while the electric starter (mounted on top of the crankcase directly behind the cylinders) spins the engine over rapidly and reliably, we couldn't help but miss having a supplementary kick starter. Granted, in a pinch, the bike could be bump started, but that's little consolation to one slight of build or a picnicker haplessly situated off the road: the American Eagle is a lot of bike to push.
Incidentally, the generator, which is located in front of the engine at the cylinder base, is driven via pulley and v-belt. But have no fear of the generator drive slipping due to oil or water on the belt, as the entire mechanism is safely ensconced within a polished aluminum cover on the bike's right side.
As one can tell from the photos, the Eagle's frame incorporates no front down tubes; rather the engine has been used as a frame member. At the upper end, the cylinder head attaches at four points to tubes extending back from the steering yoke. In the area of the pivot arm at the rear of the transmission, the engine is held to the frame by four mounts.
In this way a very rigid assembly is achieved, perhaps even more rigid than necessary, for the frame appears dreadfully heavy. The frame tubes are quite large in diameter and it seems one sees them everywhere; there are four top tubes alone. But on the other hand, it does its job very well and in that respect we shouldn't be too critical.
Suspension and running gear are of top notch quality. The front fork is a heavy duty Ceriani unit as are the rear shocks. They deliver a decidedly firm ride and keep the big Eagle well m line. Handling is positively delightful, allowing its rider to confidently carry on some very rapid roadwork. Barreling through corners you can lean this motorcycle over until you'd swear something was about to drag on the pavement. Not so. Likely you can crank it over even a few more degrees safely. We encountered no waggle or wallow which is extremely admirable for such a large machine.
By virtue of the front binder's power, braking is also top notch This brake is a twin-leading shoe affair that measures 9 in. diameter. But you must treat it gently at first, for it can put you on your melon if seized too suddenly; it must be handled gently but firmly. However, the same cannot be said of the rear brake; it is adequate, but not as responsive as the front.
Typical of many Italian motorcycles, the seat seems a bit too firm for extended periods in the saddle. Were it somewhat softer the Eagle would be one of the ultimate high speed tourers, as it is capable of sustaining speeds of 75-80 mph all day.
While the exhaust throbs with a rather authoritative basso profundo note, mechanical noise from the powerplant is minimal. If you listen closely you can hear subtle whirrings and clickings but nothing of the fatiguing magnitude displayed by most other overhead carnmers.
In all, we could not help but be delighted with the American Eagle 750. Besides providing us with enervating performance and bags of fun, our test machine also stands as an example of sorts. It proves that big bore tourers aren't necessarily trundling, elephantine mounts. They can also be sanely balanced machines capable of moving briskly and surely and stop well, to boot.
AMERICAN EAGLE 750 SUPER SPORT
$1698
