Cycle News - Archive Issues - 1980's

(Left! A low center of gravity make the Virago a fine handling machine.IRightl The Seca's shaft drive doesn't keep it from being a performer. 16 road, and accelerates real well for a 750 twin cylinder. The imponant pan is a feeling associated with a V-twin. something more emotional than logical, an esthetic appeal. The Virago delivers that with a big dealer network, parts availability and lowest price. Other Vtwin manufacturers can match one or two of those virtues, but not all three. So much for the engine. The chassis. Should anything that so resembles a Honda S65 frame work? It does, believe it. The bike handles great. The engine is slung way down there and the bike's low center of gravity makes changing direction very easy, in spite of a 60-inch wheelbase. Just a little nudge and it's a maximum lean, and with everything tucked in good, maximum is a lot Qf lean. The suspension set up as it was on our test bike worked great, too; comfortable on the bumps and even little bumps, but controlled on the corners, even fast, sweeping corners. Lean it in and the first thing that drags is the foot peg on whatever side you're leaning towards. Keep leaning and the exhaust system on the right starts to drag, along with the brake pedal, and go further and you're out of tire and out of yielding clearance at the same time. Don't do it. Stop at the pegs. We're not sure what drags after the left peg. Will the Virago have a chance as a road racer? Not with stock power. How about with the go-fast goodies Mert Lawwill is sure to develop for the Yamaha dirt trackers? No way. Modified classes usually allow wide rims and tires, and nobody will be able to fit an 18·inch rear wheel and wide slick in the swingarm, end of discussion. Also, shaft drive means no gearing available, etc. No, racer types who gotta have a Vtwin should wait for the chain-drive, Euro-V, the 920, due soon. In the meantime, the guy who is tired of nothing but fours from Japan and quirks that demand too much hassle from non-Japanese Vs can buy himself a V-twin with all the advantages of a plain Japanese four. That is, he can close his eyes, settle back, and pretend he's on something else with a V-engine. Then again. the semi-chopper seating position is so awful that maybe he won't be able to forget. Son of reminds us of those bad chairs that people in research groups have to sit in. like a theater chair, too low for the table sort of thing. Hey, how long is this test supposed to be, anyway? Am I done yet? I gotta get out of here. Got a date with an overbearing woman. Pretty nice, for a girl. Seca For years, Yamaha has been a contradiction. The only giant Japanese motorcycle manufacturer to sell large numbers of road racing machines to the public, Yamaha has also been the only one of the big companies to not sell a sporting 750cc machine. Suzuki introduced the first GS750, and Yamaha stayed with the highwayoriented three-cylinder, shaft drive XS750. Honda introduced the CB750F, and Yamaha made the XS750 into the XS850 without making it faster. Kawasaki introduced the KZ750, and still Yamaha plodded along with the XS850. Kenny Roberts won three World Championships and Yamaha advertising in the U.S.A. tried to compare Roberts' YZR500 and the XSIlOO, ignoring the slow and steady XS850. The 1980 XJ650 Four marked Yamaha's re-entry into sporting motorcycling, but the new XJ750 (also known as the Seca 750) is the company's first competitive motorcycle in the 750cc performance market. The engine is based on the XJ650: it is a pJain·bearing, 748cc eight-valve four-cylinder with a bore and stroke of 65 x 56.4mm. The AC generator is mounted on a jackshaft driven off the crankshaft by a Hy-Vo primary chain. A gear on the end of jackshaft drives the clutch. Like the XJ650, the new XJ750 has shaft drive. But in spite of shaft drive the bike is actually lighter than other 7505. Yamaha opted for shaft drive because market research showed that most buyers preferred shaft over chain. The obvious advantages of shaft are that a shaft is virtually maintenance free and much cleaner than a chain. The traditional opinion is that shaft is less efficient than chain, but Yamaha says its shaft drive system is actually more efficient than a chain. Tests between the XT500 chain drive and the XJ650 proved that the shaft actually lost less horsepower to friction than the properly. lubricated. properly adjusted chain. The Seca 750 is billed as a sports bike and a performance machine. The claims are backed up by photos of Roberts riding the bike at Laguna Seca, the California track after which it is named. It is hard to argue at least part of Yamaha's claim. In preliminary testing in Los Angeles, a Seca 750 ran the standing start quarter mile in 12.4 sec., an excellent 750cc time and competitive with other sporting 750s. Like the XJ650, the XJ750 engine makes its best power above 6000 rpm and fairly screams when the revs are kept up. Unlike the 650, the Seca 750 has rigid engine mounts, but doesn't seem to lose any smoothness as a result. The engine is very smooth. The Seca bristles with hightechnology features. The YICS system (Yamaha Induction Control System) is seen on a number of other Yamaha models this year. When the intake valve opens. fuel/air mixture is drawn into the cylinder through the normal intake port and also through a YICS sub-pon which intersects the main pon in the head. The main ports draw through the 32mm Mikuni CV carburetors. But the sub-pon draws from the intake tracts of the other cylinders. Since the sub'pon is small diameter. the fuel·air mixture travels through it at a speed about four times faster than the mixture in the main port. The high-velocity stream from the sub·port creates a swirl directed into the cylinder. The swirl agitates the cylinder charge. making it more even and improving efficiency. The Seca has a computerized monitor system. with liquid crystal displays on the instrument panel to warn the rider of any problems. If the battery fluid is low, a LCD reading "Batt" comes on as a red warning light flashes. If the taillight bums out, a LCD reads "Tail" and the warning light flashes again. Even the fuel gauge is LCD, divided Yamaha XV7&O VIrago Speclftcations .................................--co a x-.aw..................................... oIed V-twln. .ahc Engine Bore X strole. Dispf8cetnent •••.•••••••••••••••••••••.••••.•.••.••••••• 7ecc CcHnpr..-ort nnio.......................•.......•...•••.. 1.7:1 Ignhion..,- 5 ... tiliQ lyatem .......................... 11.,1I1e only_kick) •....•.•••.••.••.•.•.•.•.•••..•••••.••1.,1rGnic Lubric8tIon •••••••••••••••••••.••••..••.•••••••••••• wet ....... Clutch ........................................ wet,. ........... Dry V.telght . • . . . . • • . • • . . . . • • . . .•.......•....••••.•• .,. pounda Wh .1...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . .• 80 inchea Fuel tank C8f)8Cit, •.••.•..•..'...•.•...•••..••..••••••• 31 F"OUI Prirnery drive ............................................ __ FineI drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • • . . . . . . IIh8ft T....*ftl••lon .........•.....•.........••...•....•.•• five 'P•• d Seet :=.......................................... Retail 2I1nchea ............................................. ~ Yameha Seca 150 SpecIfications EngIne •.....•............••••.•....•.•.•• cool.... 4-cyL. dahc Bore lit st:roka ................... ,. ••••••••••••••••••• x. . . . . OIeplecelnent ........................................... 7ecc CoIrLpr' 1111- nnio......................................... 1.2:1 SI:Iii ling a y _ II Ie ....................................... Ignhion . . , - . ........................... II• •11... .... ~ ••••••••••••••••••••••••••••••••••••••••• wet~ CIIItctt •••••••••••••••• wet,. m..... P'111 Dry wlight ......................................... 474 ,aUR .... It • • • • • • • • • • • • • • • • • • • • • • • W'Il••.,.......................... Fuel tank e::tII~ty ............................................... ~-~, Pi~, .............................................................. fill!' 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