Deltabox magic
It handled very well for the time and the engine was superb with usable power liberally sprinkled all over the rev range but the brakes on the early version were not perfectly matched to the stunning performance of the power plant. The silkily smooth four cylinder engine was almost bullet proof, incredibly for the time the top end didn’t need servicing until 20 plus thousand miles had been covered, although the odd one or two did have a small problem with stretched con rods particularly if they had been raced. Thankfully Yamaha stuck with the layout of the engine and concentrated on improving the rest of the package instead as the early chassis was mere a product of its time while the five-valve per cylinder slanted design was years ahead of it.
The main feature of the FZR model type is the huge Deltabox beam frame that has since become the accepted norm, Ducati’s steel trellis apart of course, in all types of modern day machinery from Superbikes to Motocross and trials bikes. The motorcycle industries affair with such gimmicks like anti dive or air assisted forks and sixteen inch front wheels was finally over the results being seen with the Yamaha FZR.
Of course we in the UK only received the 1000cc version until the introduction of the OWO1 in 89 but in Canada, the US and Japan the much sweeter FZR 750 was released on to the willing population. Forever after that moment beam frames, trick suspension and water-cooled engines were very much the order of the day. Light weight power house machines that were fast and handled with race track like agility have since been the leaders of every major manufacturers range with each year on seeing improvements, albeit some small, on that original 20 year old concept.
The engine was, either by design or complete accident, the perfect shape for the next generation of machines with it bank of cylinders raked forward 45 degrees from the vertical allowing the frame tubes to run straight over the top rather than having to curve around and hence be significantly stronger. The power delivery was impressive too with over 105 bhp on tap with the very first version and rising significantly with every year of development. Despite being ridiculed by the press and opposition as nothing more than a gimmick the 20 valve cylinder head design did exactly what the Yamaha design team claimed and the five valves in each pot, placed radially around the combustion chamber, went on to power the whole tuning fork sports bike range right through the next fifteen years. Of course this technology was an offshoot of the Yamaha 3.5 litre V 8 F1 car engine first seen in the Zakspeed 891 chassis.
The water-cooled four-cylinder engine is supremely tractable and smooth with faultless carburetion all the way to the 10,500rpm ceiling where the power tops out and the rev limiter starts to wake up ready to kick in at a tad over the eleven marker. The performance of the power plant is highlighted when ridden back to back with the Gixer as anything the Suzook lacks is there inside the Yamaha waiting to be untapped.
The chassis is both strong and immensely versatile with every aspect of the suspension being fully adjustable in keeping with the racetrack heritage. This results in a superbly responsive and confident vehicle upon which it is oh so easy to travel both quickly and safely on. The riding position is most unlike a sports machine with the seat very low in relation to the handlebars giving the wrists an easier time than the Gixer and many similar machines.
Manoeuvrability is superb despite a relatively lengthy frame and wheelbase thanks to the weight of the fuel tank being slung low way down where the carbs and air box would normally sit, they are positioned up near the steering head snugly residing between the two frame rails in the area normally reserved for the cylinder head.
With the air box removed the carbs can be clearly seen pointing vertically, directly down into the inlets rubbers, this give the engine tremendous breathing ability and has since become the accepted norm in sports machinery along with so many other features of this machine. Compared to the Suzook the Yam is a little heavy but with a few extra horses on tap, around twenty to be precise, the difference on the road is minimal and handling apart once revving up near double figures the two bikes share a similar level of performance. Once tipped on its ear the FZR, unlike its mate, stays put and tracks true never giving cause for concern even at some ridiculous rates of knots. The huge beam chassis never loses its composure or if it does, I for one wouldn’t like to be on it when it gets squirmy, as it would surely be just before what is known in the trade as an off!
Once again the brakes are literally years part in performance feel and character the Gixer callipers are throwbacks from the late seventies while the yam uses large disc rotors and a longer pad area to create a sublime stopping experience of course the use of radial tyres that the 17” front wheels allows, helps the feedback from the roads surface no end.
A year later the FZR750 grew into the “Real Deal” OWO1 that saw action in many theatres of operation throughout the globe from world Superbike to top level national racing, proving to be an effective tool both on the track and, for those lucky few who could afford to put one there, on the road. The basic engine and chassis design lived on well into the nineties and beyond with the Thundercat, the Thunderace, the YZF-R7 and R1 all using the five valve per cylinder technology and derivatives of that 1985 FZ mill. Little hard facts are known but the concept is almost certainly still used in the YZF-M1 Moto GP machine that sits underneath Mr Rossi and the word Deltabox is still banded about for the frames used in all of Yamaha’s racey machines.
Yamaha FZR750 specifications
- Engine – liquid cooled, 20 valve DOHC, in line four
- Capacity – 749cc
- Bore & Stroke – 68mm x 51.6mm
- Power – 121bhp @ 11,500rpm
- Torque – 55ft lbs@ 8500rpm
- Transmission – six speed, chain final drive
- Carburetion – 4x Mikuni BD 34 mm downdraft
- Chassis – aluminium “Deltabox” beam frame
- Suspension – 41mm telescopic forks, single shock “ Full Floater” rising rate rear
- Brakes – 2x 310 mm discs four piston calipers, 220mm disc, twin piston caliper
- Wheelbase – 1470mm
- Weight – 228kgs
- Top Speed – 162mph
Yamaha FZR750 Road Test Gallery
[dmalbum path=”/wp-content/uploads/dm-albums/Yamaha FZR750/”/]
