Fuel Injection
Fuel Injection may not be new in the two-wheeled motorcycle world, but it is now slowly starting to make its mark in two-stroke trials machines. Tried, tested, and accepted in the four-stroke trials world since 2004 with the hugely successful Cota 4RT engine used in both the Montesa and Honda trials machines, its ability to deliver the fuel electronically has worked very well in both performance and reliability. Quite new as a motorcycle manufacturer in the trials sector, the go-ahead Vertigo brand has used the calibrated control of delivering the fuel into a cylinder barrel since it arrived on the trials scene in 2014. As we move through 2021 with more of the 2022 motorcycle trials models imminent, maybe we will see some of the other two-stroke manufacturers move away from the mechanical control of a carburettor for the fuel delivery changing to Electronic Fuel Injection; wait and see.
Mechanical carburettors have been around in the same shape or form from the turn of the century on motorcycles as a way to mix air and fuel proportionally before it is drawn into the combustion area. The flow can never be accurately controlled mechanically. Still, with an electronically-controlled system, the calibration is much more accurate and delivers the exact amount of air-fuel mixture, providing greener emissions out of the exhaust.
We have to take a step back in time to just over 40 years ago to start to understand the history of fuel injection in motorcycles to the early ’80s by one of the big four motorcycle manufacturers from Japan, Kawasaki. As far as we know, they were the first motorcycle manufacturer to use fuel injection on a commercial basis in 1979 on their mind-blowing six-cylinder, water-cooled, four-stroke Z1300 model; yes, close on 1,300cc of power between your legs! During its 10-year production cycle, they moved from mechanical carburettors to fuel injection, primarily for better fuel consumption and not engine performance.
FUEL INJECTION – TRIALS TESTING 1974
In the early ’70s, with the Japanese in motorcycle trials arriving on the scene, both Honda and Yamaha changed their thought pattern of the future of the trials motorcycle. Honda went down the four-stroke route with Sammy Miller, and Yamaha employed the services of Mick Andrews to develop a new two-stroke trials model range. As Miller worked to cure the four-stroke ‘cough’, Yamaha took another route into developing the two-stroke engine, first with reed-valve cylinder induction on the twin-shock TY model range. They would then move to a type of basic fuel injection for the first time on a trials motorcycle never seen before.
In 1974 they presented Mick Andrews with their radical single rear shock absorber machine, the Cantilever as it was called at the time. The prototype machine’s official title was the Yamaha YZT 250cc, and it gave the trials world its first vision of something similar to fuel injection. The fuel feed system on Andrews’ machine used a ‘May Pump’ invented by a German engineer. It controlled the fuel
supply to the cylinder by measuring vacuum pressure in the crankcase when connected to the carburettor by a rubber hose. It allowed the removal of the floats inside the carburettor bowl though it still retained a needle and needle jet. There would be no ‘choke’ lever to start the machine, but Mick would squeeze the rubber housing at the base of the carburettor to generate pressure, a form of priming before the engine would fire into life. It would then regulate the crankcase pressure through the rubber hose back to the carburettor. This air-fuel mixture worked through a diaphragm while it was running to deliver the correct amount of fuel at any one time.
Andrews claimed the machine would run upside down, if necessary, without any change detected in the engine’s running performance! He won the 1974 Scottish Six Days Trial on this revolutionary motorcycle before the ‘May Pump’ idea disappeared from the trials scene. Maybe it will reappear as the Yamaha single rear shock design did until the aptly named Mono-Shock model appeared in 1983 and changed the face of the trials world forever; who knows.
FUEL INJECTION – OFF-ROAD RACING 2000
Would you believe that the good old USA produced the first production off-road machine with electronic fuel injection, which came from Cannondale in 2000? It was headline news as the great America hoped to challenge the rest of the world, but the dream soon passed and disappeared in a few years.
European engineers then took the reins as Gas Gas introduced its new EFI, 450cc four-stroke Enduro machine in 2002, followed by Aprilia, Husqvarna and Sherco quickly followed by BMW and Husaberg in 2009 with their Enduro models. From Honda, Kawasaki and Suzuki, Japanese engineers followed suit on their motocross machines during the 2008–2009 season as Yamaha finally went EFI over a four-year period from 2010–2014. Wanting to keep pace with developments, KTM joined the race with its range of Enduro and motocross machines in 2011 and 2012.
FUEL INJECTION –
TRIALS EXPERIMENTS 1996
European innovation in the motorcycle trials world has come from many talented riders and engineers over the years. In the past 40 years, names spring to mind such as John E Shirt (GBR) Yamaha, Jaime Subira (ESP) Fantic, Pedro Olle (ESP) Beta, Josep Paxau (ESP) Gas Gas and Sherco, and Josep Serra ‘Xiu’ (ESP) Gas Gas and Ossa, to name but a few.
With the introduction of the first water-cooled production trials model with Aprilia in 1989, the aluminium framed production Beta in 1990 and
the crankcase induction on the Gas Gas in 1993, many wondered what would come next.
In a closely guarded secret, various factories played with the controlled fuel delivery concept — or variants of the fuel injection theme — before it surfaced in 1996 with Gas Gas. Josep Paxau was working in Gas Gas’ research and development department in Spain on various projects. He wanted to explore the implementation of fuel injection on the two-stroke trials engine. Working alongside two other, younger engineers, Josep Parres and Toni Garrido, they fitted a very early electronic system to various engine capacities of Gas
Gas machines to understand the working of the EFI in the slow-speed world of trials. After downloading all the data and information, they looked at various areas where they could start to improve the machine’s performance in all situations.
In 1997 Paxau moved to the rival trials manufacturer Sherco and took his ideas with him. Over the following years, he would look at the workings of the fuel injection system on both two- and four-stroke trials machines. Despite encouraging results, Paxau was worried about the downside of the early EFI systems for the buying public, such as the consumer perceptions of computers and the complexity of the electrics involved, and an aversion to the re-mapping of the engine with PC software still in its infancy. The general public was more familiar with changing slides, jets, and needle positions in the mechanical carburettor. They also understood the ease of adjusting easily accessible air-mixture and idle screws. ‘Why change something that is not broken?’, was the mindset.
FUEL INJECTION – FOUR-STROKE 2004
It would take the intervention of the HRC department of the mighty Japanese motorcycle giants Honda, in association with Montesa, to be the first manufacturer to use EFI on a production trials machine with the introduction of the new Montesa Cota 4RT in 2004. Using the single-cylinder four-valve OHC CRF 250cc motocross motor as a base point for the Cota 4RT trials project, its fuel supply to the engine was supplied by a lightweight, simple integrated injection system. Abbreviated to PGM-FI, it would work with a lower volume than a conventional carburettor to suit the needs of the variable parameters found in the trials motorcycle. The ECU is an intelligent, high-precision control unit that would work in association with the throttle body and control unit. Using electric sensors, it would perform instantaneous calculations of a wide range of variables such as the environment, engine temperature and atmospheric pressure to give the optimum performance from the fourstroke engine. To make the whole EFI system work, first it would need a source of power, but with this came the extra weight of the addition of a battery. Using their full resources to avoid the use of a battery, HRC introduced a system in which the kickstart pedal activates an extremely high-performance generator. It would provide the ECU with enough power
to run the fuel injection system pump, in turn guaranteeing a quick, reliable starting method of the motor with a slow, strong depression of the kickstart lever.
It worked, and the idea was a world first in the motorcycle world. Such was the engineering excellence applied in the design of the engine, it would also meet the newly introduced impact of the EURO2 regulations concerning emissions which had to be strictly adhered to. Such was brilliance in the design and application of this four-stroke engine in 2004, it has stood the test of time to be still delivering worldclass performances; 28 FIM Trials World titles in the hands of Toni Bou says it all. The Respol Honda powered by the Cota 4RT remains the one to beat in his capable hands in 2021.
FUEL INJECTION – OSSA 2009
As you will find in our two-part Ossa story starting in this magazine, the Spanish manufacturer was the first to apply electronic fuel injection to a production twostroke trials motorcycle.
Introduced in November 2009, the new production 280cc Ossa trials machine broke new boundaries with its reverse cylinder technology and introduced the EFI Kokusan batteryless system. It mirrored the four-stroke Cota 4RT engine with the facility to electronically adjust the machine’s performance to suit changing conditions. It was also similar to its four-stroke counterpart in its starting procedure, unlike a conventional two-stroke.
To start the engine and correctly set the injection system, you would close the throttle and take the kickstart lever through its full stroke to generate enough power to activate the electronic fuel injection before the engine would fire into life.
Applied to the two-stroke engine, the EFI gave it a soft and linear performance with no sudden power surges, and the opportunity to stall the engine on even very low throttle openings had vanished. Sadly, Ossa as a motorcycle manufacturer, disappeared in 2015.
FUEL INJECTION – VERTIGO 2014
As the Milan show opened in November 2014, it introduced the brand Vertigo, a new motorcycle trials manufacturer from Spain who would take the EFI application to another level.
Tucked nicely into its trademark trellis-type steel tubular frame was an ultra-compact 300cc two-stroke engine. It would benefit from a bespoke electronic system representing the latest advances with the ECU managing and controlling the engine’s performance in all situations. The advances made in the use of the EFI were simply mind-blowing. With a choice of four different maps, it offered an unequalled level of engine adjustment in the world of trials for user refinement.
The complexity of the ECU would precisely adjust the fuel injection in conjunction with ignition settings to provide exceptional and smooth power delivery to match the terrain and riding performance for the rider. To start the Vertigo would require a simple technique to work in conjunction with the EFI by gently applying pressure on the kickstart lever to engage the kickstart gears. You would then relieve the pressure and apply a solid stroke to ensure the engine is able to start.
As we now know, the Vertigo success story made it a huge hit with the buying public as it achieved notable victories with Dougie Lampkin and James Dabill in both the Scottish Six Days and Scott Trials proving the machine’s reliability. As to be expected with any new motorcycles, a few early problems were soon eradicated, and the model’s EFI has now become a bonus selling point of the machine’s ongoing success story.
FUEL INJECTION – HOW DOES IT WORK
Believe it or not, it is far less complex than you would imagine and much more reliable in its performance than a carburettor. With only two main components: a butterfly valve and an injector nozzle, the system is far simpler than you would think. The control of these technical components is where it gets more electronic. A range of sensors constantly measures different variables such as the RPM of the engine, coolant temperature and ambient air pressure, which all control the running of the engine, therefore, adjusting itself to create the perfect performance output. To make this all come together, the fuel mixture needs to be cleanly delivered directly to the crank, hence the control from the EFI.
Any two-stroke engine requires a nice clean mixture that gets the maximum fuel charge into the cylinder to combust. The precise control of the mixture also has the added benefit of helping to cool the engine efficiently, another key factor in achieving maximum performance.
EFI does not provide any significant power increase. Still, it does allow for creating precise mapping, power curves and help improve the fuel range of the machine as it becomes more efficient and uses less.
An EFI uses its brain to think all the time, and the parameters of the adjustment are very precise. They work at a much faster rate than a throttle opening action using a carburettor. To adjust Vertigo’s GET electronics, a Wificom device was introduced. It will allow you to connect to the ECU, which works alongside a mobile app to make various adjustments and checks on your Vertigo with a WIFI connection from your phone or tablet. Maintenance is very low due to the air filter positioning and having no carburettor to clean on EFI machines, making them very ‘Wash and Go’ and riderfriendly.
FUEL INJECTION – THE FUTURE
As we move swiftly towards 2022, fuel injection systems also score top marks concerning environmental issues. Essentially, being a sealed unit, they don’t allow unburned fuel escape when the motorcycle is parked and not running. Emissions will control our future as we all try to protect the environment, and the application of an EFI unit does provide a positive future for fuel-aspirated engines.