R6 Prototype


Big bikes have more power, but you can't ride them as hard in the turns.  You can ride this 400 hard -- really hard -- because everything feels right.

--Eddie Lawson, after testing the new FZR400
at Laguna Seca International Raceway in 1988.

IN 1988, YAMAHA TOOK AN unprecedented step by importing a class of sportbike into the United States that had previously been available only in other countries.  The machine had a combination of features and attributes never before seen on an American-sold sporting motorcycle.  The bike was the FZR400, and it has the distinction of being the first and only motorcycle of its class to be imported into the United States -- ever.


The new YZF-R6 in European trim.There have certainly been other 400 cc bikes.  Some of these machines, like the Honda CB400F and CB-1 and Suzuki Bandit 400, have been inline fours; others have been twins and singles, in both 2- and 4-stroke variants.  There have also been other lightweight sporting machines, such as the Hawk GT with its twin-beam aluminum frame and single-sided swingarm.  But the FZR400 was the bike that handling junkies, racers, and road test editors had been clamoring for, and the only one designed to go directly from the showroom floor to the racetrack (which most did, cleaning house on everything in sight).  However, when Yamaha served it up at a price higher than any competing 600 cc machine -- including its own FZR600 -- it underwhelmed the buying public.  And so it came to pass that what many have called the finest-handling streetbike ever to come to these shores died a sure, albeit slow, death.  It was three years before the machine faded from Yamaha's lineup, but before the tiny Fizzer gave its last gasp, it set the sportbike and clubracing world on its collective ear.


Just what did this bike have that caused magazine editors to scramble for the keys when it was time to head for the canyons, and serious club racers -- including Kenny Roberts Jr., who cut his racing teeth on one in 1990 -- to hock everything up to and including their firstborn to get their hands on one?  In a word, handling.  This bike was as close to a half-liter GP bike in its overall proportions and chassis dimensions as anything available.  Its chassis numbers set a benchmark which is currently duplicated by every hardcore sporting machine available, including the Ducati 916, the GSX-R 600 and 750, the YZF-R1, and the CBR600F4, to name just a few.  But it wasn't just the dimensions and numbers that set the machine apart, or made it work as well as it did, and still does.  The numbers -- 24 degrees of rake, 3.5 inches of trail, and a wheelbase of 55 inches -- set the standard for every successful sportbike which has followed the FZR400 onto the racetrack or street.  But the features that allowed the machine to get the most out that combination of numbers were just as radical and just as important to the overall package.


The starting point for a superior sportbike: a stout chassis.To start things off, Yamaha engineers gave the FZR400 a massive Deltabox frame.  Two enormous, welded box-beam frame spars were mated to an incredibly stout steering head, which was gusseted with a thick aluminum plate for extreme rigidity.  The beams terminated at massive aluminum castings which bolted to the engine, swingarm, and subframe.  The general layout and geometry of this frame reflected a close adherence to the chassis technology in use on Yamaha's 500cc GP machines, which were devouring the competition.

The use of the short-stroke, high-revving 400 cc Genesis engine allowed the designers to push the power plant well forward in the frame.  This let them use the space behind the engine to excellent advantage, as well as place more weight on the front wheel.  The large 4.8 gallon fuel tank is concealed under the plastic tank cover, and extends deeply into the space behind the carburetors.  This keeps the weight low and well-centered.  The airbox is an enormous 7.7 liters, much larger than the even the 6.5 liter piece on Honda's new CBR600F4.   (As an aside, a large airbox improves throttle response when the butterflies are yanked open -- the size of the opening and type of air filter determines the flow at a steady throttle position.)


Note the massive gusset welded between the frame rails.This frame, which was far stronger and stiffer than needed to cope with the modest horsepower of the 400 cc engine, was equipped with the widest wheels ever seen on a sub-1000cc streetbike up to that time.  In fact, the 3.00 x 17 and 4.00 x 18 front and rear hoops on the FZR were a half-inch wider than those that came on the Honda Hurricane 1000, one of the fastest machines of its time.  The reason for using those massive wheels was simple, in Yamaha's view: this bike was designed to corner fast, and corner hard.  That's what the huge wheels and ultra-stiff chassis were all about.


Today, that's still what it's about.  And the Yamaha still delivers because it came with the goods to begin with.  The 400 cc engine serves up about 55 rear wheel horsepower in California trim, with a smooth, manageable dose of respectable midrange thanks to the EXUP system.  Most of the power is concentrated above 10,000 rpm; to really make time, a good rider will learn to keep the engine above that mark on the tach, which redlines at 14,000 rpm.  Even today, at 370 pounds dry and about 410 wet, the bike is anathema to larger sportbikes if wielded by an experienced rider.  Keep the cornering speeds high and the engine on the boil, and as often as not you'll be running out front on the Fizzer, or at least keeping the big boys in sight.  It's not until brute horsepower comes into play that the bigger bikes disappear over the horizon.


The 600 mill is shoehorned into the 400 frame, but but does fit.That's where the 600 cc solution comes into play.  It wasn't long before powermad racers and street riders learned that the FZR600 engine was nearly a direct bolt-in to the FZR400 chassis, which was far superior to the heavy, flexy, steel item with which the FZR600 was burdened.  Experienced racers knew that the FZR400 would let them get away with things that the 600 would not tolerate, particularly high-speed shenanigans.  The FZR400, if set up properly (which includes tossing the rear shock in favor of any decent aftermarket item, and sorting the forks a bit), is very quick handling without the slightest hint of being twitchy, and it is also rock solid at triple digit speeds, even at crazy lean angles.  The FZR600 just never came close at the racetrack.


Click for larger image.A number of experienced racers built FZR400 superbikes, for which Yamaha provided a wide variety of special racing components.  One of the most notable was a machine owned by Jeff Short, of California's American Federation of Motorcyclists (AFM).  The bike was designed to race in the unlimited displacement, anything-goes Formula 1 category.  It had an engine built from a variety of parts which came from the YZF600, FZR600, and FZR400 engines.  The total displacement was 661 cc, which produced 112 horsepower at the rear wheel.  The machine weighed in at under 300 pounds in race trim.  Short took an amazing third place, fighting his battle with 1100 cc machines that had been built to the hilt.  The reason for his astonishing performance (aside from his talent as a racer) was because the essential qualities of the FZR chassis allowed him to out-maneuver much of his competition.


Several street riders built 600 cc versions of the FZR400, with varying degrees of success.  Some were butcher jobs, some were fair, and a few were exceptional.  The machine featured in this article is owned and was built by Jay McDaniel.  It represents one of the best examples of the conversion we have come across.


Enormous radiator barely clears the frame and headpipes. Click for larger image.The biggest problem with this project is providing adequate cooling for the 600 engine.  This problem was solved by using a Yamaha racing radiator and intercooled oil cooler, features which are standard equipment on the YZF600 and R1.  This radiator is nearly twice the size of the stock item, and substantially larger than the 600 piece, which can also be used.  The cooling fan does not fit with the much taller 600 engine, but with the racing radiator, it's not needed.


The ignitor box for the 600 engine must also be used to retain the proper ignition curve, EXUP control circuit, and limit on engine speed.  On this machine, the ignitor box was relocated from beneath the seat to a spot under the tail section.  The OEM airbox will not fit, so individual filters were used on the stock Mikuni carburetors.  The EXUP exhaust must be used if driveability and torque are an issue, which they were with this street machine.  The carb settings were left alone, other than to bump the main jets up four sizes to compensate for the drastically increased airflow through the individual filters and straight-through, 2" diameter exhaust canister.  This creates a slightly rich condition through the upper midrange with a monster kick on top.  A five-degree static advance key was used, which also increases peak horsepower and helps deliver crisp throttle response from idle to redline.


Click for larger image.To cope with the drastically increased power, a 520 chain conversion was fitted.  The machine is most often shod with Pirelli MTR01 and MTR02 Dragons, a modern tire with excellent street and track performance.  The fork springs and shock were replaced with aftermarket items.  The forks were carefully set up to compensate for the additional weight and power of the 600 engine.  Initially, there were problems with the forks topping out under acceleration and bottoming under hard braking as compared with the 400 engine.  Precise adjustment of the oil level, along with a heavier oil and proper preload and ride height settings resolved those problems.


This machine has been to several track sessions at both the Streets of Willow and Willow Springs International Raceway, where it performed extremely well.  Under real-world conditions, because of the combination of light weight and horsepower, the machine is able to handily pull away from many middleweight and even 750-class machines, as well as some 900 and liter-sized twins.  The long-stroke FZR600 mill lets the rider lug the engine and still get a good drive out of tight turns, while the nasty kick on top lets the bike out-distance much newer hardware on the straight stuff.





600 conversion wears Erion Racing Titanium canister.On the road, in the real world, this bike has proven to be an extremely potent backroad toy.  It consistently displays the amazingly good handling manners for which it was lauded when it first arrived in the USA; that legendary handling, coupled with 600 cc power, frequently leaves many riders of much larger or more hightly-touted sportbikes wondering where the nitrous bottle is hidden.  On a recent weekend ride, the 600 conversion went head-to-head with the brand new VFR800FI and BMW R1100S, the flagships of their respective marques.  The venue was Central California's infamous Santa Rosa Creek Road, a mostly one-lane, tortuous piece of pavement that is a tight as it is unpredictable.  The decision went to the FZR.  Its light weight, terrific brakes, and precise, confidence-inspiring handling, combined with a gut-wrenching second gear lunge from Santa Rosa Creek Road's mostly tight turns gave it the nod.  The machine is particularly competent under hard braking.  It has very little tendency to stand up while trail braking; it is very easy to modulate speed even while very hard on the brakes because of the stiffness of the chassis, light weight, and precision of the handling.  Stainless steel lines and aftermarket, high-carbon brake rotors and Kevlar-carbon pads up front help tremendously in this area, and are a must for the aggressive rider if the 600 engine is fitted.


This variant of the FZR400/600 conversion has by no means reached its zenith.  The cast iron cylinders of the 600 top end can be punched out to 630 cc and fitted with high compression pistons, netting about another ten horsepower on top with 4-5 more foot-pounds of torque.  More radical cams can be fitted, further boosting the engine's power output.  With the cams, 630 cc high compression kit, and Stage 3 jet kit and pipe, this engine can easily attain 100 rear wheel horsepower while being extremely streetable (if the EXUP is retained).  The cost of such a project would be far less than the purchase of new 600; a used FZR400 can be had for around $2500.  A low-mileage 600 engine (and there are tons of them available) can be purchased for another $1000.  Even figuring another grand for items like brake rotors, pads, a chain conversion, and odds and ends, the project is still a lot less cash than any currently available 600.  When it's considered that such a machine will not only be unique, but will outperform its heavier competition in most real-world situations, it becomes an attractive option to the motorcycle enthusiast who likes to have his hands come between him and every part of his motorcycle.  The older machine is also far cheaper to insure and register.


This is the machine many said Yamaha should have built ten years ago.  For various reasons, no marque has done so until now.  For 1999, both Honda and Yamaha will have 600 cc machines in exactly the same weight category as the FZR400/600.  These bikes, the CBR600F4 and YZF-R6, produce 15-20 more horsepower than the FZR400/600 conversion, have stouter suspension components, and better brakes.  On the racetrack, they would no doubt leave the homebuilt hybrid in their collective wake; in the serpentine canyons of Southern California, where the FZR400's more slender profile and substantial torque create a modicum of parity, and where law enforcement and due consideration of one's mortality are part of the equation, the little Fizzer may yet hold its own.  We're looking forward to the test.

Editor's note:  All comments, comparisons, and opinions regarding the handling or performance of evaluated motorcycles are made with the assumption there is a skilled rider at the controls.  Machinery is no substitute for experience or training.

Copyright 1998 by Dan Axton.  All rights reserved.
 Interactive Motorcycle.