Vance & Hines Yamahafzr600
VANCE & HINES YAMAHAFZR600
ON THE GAS
WITH A FLICK OF A TOGGLE SWITCH, "BABY Stealth"-as christened by its creators-is armed and ready to deliver a punch that could knock a Scud from the skies over Tel Aviv.
When selected to participate in Cycle World's firstever Built For Speed 600s competition, Vance & Hines Motorcycle Performance Products (14010 Marquardt, Santa Fe Springs, CA 90670: 213/921-7461) took on the task with th~ seriousness of' a gov ernment weapons contractor. l'hev went after killer performance numbers with a vengeance. putting the `squeeze'' on an already potent FZR600 motor by plumhiii~ in a nitrous-oxide-injection system.
Vance & Hines sells an OS Systems kit designed for motorcycle applications. The system delivers a cool, dense. oxygen-rich charge into the intake tracts, which has the efI~ct of supercharging the combustion chambers. 1 he mechanics of the NOS system are sim pie enough: A refillable bottle containing 2 pounds of nitrous-oxide is connected via a steel-braided line to a solenoid-actuated valve. The pressure of the N20 is between 600I 1 00 psi. depending on bottle tempera ture. On the \`&H F/R. the system is triggered at full throttle b~ a switch connected to the throttle linkage that sends electric current to the solenoid, opening the valve. With over 600 psi prodding it along, it's easy to imagine the ) flowing through the plumbing that feeds an injector nozzle in each intake port.
It is critical that the proper ratio of enrichment fuel is injected into the intake tract along with the nitrousoxide, in order to maximize performance gains and avoid an extreme lean condition that would do serious damage to the motor. Thus, the enrichment f'uel is also controlled by a solenoid-actuated valve, and is plumbed in a similar fashion to the N20. with an elec tric pump supplying fuel.
A 2-pound bottle of nitrous-oxide doesn t last long. so I3ah\ Stealth needed sonic internal oomph br run ning when the sciueeze gave out. A balanced eranL shaft carries a set of ( arrillo rods and \ ance & II ines pistons that boost displacement to 6 I `)cc and cornpression ratio U) 1 2.5: I . I~he cvi mdci head received complete roadrace portilig and competition val\ e job. as well as a set ot Vance & I lines cams with titanium valve-spring retainers. ulie transmission gear dogs were undercut to ensure positive engagement. I lot rod motors tend to run hot. so an ( )W( ) I rad ma tor off'ering greater cooling capacity was fitted.
The trickest techno-piece on the hike, however, is the Vance & Hines l~owerpak Ignition box, which has recently become available f'or F/Rs and Suzuki ( iS.\ Rs. The Powerpak allows a tuner to select up to I (`~ different combinations of ignition timing and re' limit, depending on the specific engine configuration or riding application. It also has the ahil tv to retard the timing when the NOS system is triggered, thus delivering optimum power gains from the juice.
Due to the increased power output-arid particu lark the sudden load produced by the nitrous-oxideVance & limes needed to address i3abv Stealth's most-likely weak link: its clutch. Byron II ines (Icsigned a clutch-lockup device that bolts on the outside of the clutch pressure plate. using the clutch-spring bolts as mounting points. As engine revs increase. centrifugal force causes five [-shaped arms attached to the device to pivot and push against the pressure plate. The arms can he tine-tuned by adding weightin the form of Allen bolts-to their ends.
All this trickery. of course. has a Cost. While select hits of the Vance & limes IZR could he employed rather economically on a standard-issue [[ZR. spring ing for full-military power has it downsides. About I 5.000 of them, which is the estimated dollar figure that it would take to slot a Baby Stealth into your own personal. bomb-proof' hanger. At that price, a con tract to build a squadron of Baby Stealths for civilian use is highly unlikely. -Don Canet
