1. Techa Tipz: Motorcycle EFI vs Carbs
1] Differentiation between EFI and Carburator type,
Carburetor system:
Principles:The carburetorworksonBernoulli'sprinciple: the faster air moves, the lower its static pressure,
and the higheritsdynamicpressure.The throttle (accelerator) linkage does not directly control the flow of
liquid fuel. Instead, it actuates carburetor mechanisms which meter the flow of air being pulled into the
engine. The speed of this flow, and therefore its pressure, determines the amount of fuel drawn into the
airstream.
A carburetor basically consists of an open pipe through which the air passes into the inlet manifold of the
engine.The pipe isinthe formof a Venturi:itnarrowsinsectionandthenwidensagain, causing the airflow
to increase inspeedinthe narrowestpart.Below the Venturi isabutterflyvalve called the throttle valve —
a rotating disc that can be turned end-on to the airflow, so as to hardly restrict the flow at all, or can be
rotatedso that it(almost) completely blocks the flow of air. This valve controls the flow of air through the
carburetorthroat and thusthe quantityof air/fuel mixturethe systemwill deliver,therebyregulatingengine
power and speed. The throttle is connected, usually through a cable or a mechanical linkage of rods and
joints or rarely by pneumatic link, to the accelerator pedal on a car or the equivalent control on other
vehicles or equipment.
Fuel isintroducedintothe airstream through small holes at the narrowest part of the Venturi and at other
placeswhere pressure will be loweredwhennotrunning on full throttle. Fuel flow is adjusted by means of
precisely calibrated orifices, referred to as jets, in the fuel path.
Fuel injection isa systemforadmittingfuel intoaninternal combustionengine.It has become the primary
fuel deliverysystemusedinautomotive engines,havingreplacedcarburetors during the 1980s and 1990s. A
variety of injection systems have existed since the earliest usage of the internal combustion engine.
The primary difference between carburetors and fuel injection is that fuel injection atomizes the fuel by
forciblypumpingitthroughasmall nozzle underhighpressure,while a carburetor relies on suction created
by intake air accelerated through a Venturi tube to draw the fuel into the airstream.

2. Modernfuel injectionsystems are designed specifically for the type of fuel being used. Some systems are
designedformultiplegradesof fuel (usingsensorstoadaptthe tuningforthe fuel currentlyused).Mostfuel
injection systems are for gasoline or diesel applications.
The functional objectives for fuel injection systems can vary. All share the central task of supplying fuel to
the combustionprocess,but it is a design decision how a particular system is optimized. There are several
competing objectives such as:
• Power output
• Fuel efficiency
• Emissions performance
• Ability to accommodate alternative fuels
• Reliability
• Drivability and smooth operation
• Initial cost
• Maintenance cost
• Diagnostic capability
• Range of environmental operation
• Engine tuning
The moderndigital electronicfuel injectionsystemismore capable atoptimizingthese competingobjectives
consistently than earlier fuel delivery systems (such as carburetors). Carburetors have the potential to at
Driver benefits
Operational benefits to the driver of a fuel-injected car include smoother and more dependable engine
response duringquickthrottle transitions,easierandmore dependableengine starting, better operation at
extremely high or low ambient temperatures, smoother engine idle and running, increased maintenance
intervals,andincreasedfuel efficiency.Onamore basic level,fuel injectiondoesawaywiththe choke,which
on carburetor-equippedvehiclesmustbe operatedwhenstartingthe enginefromcoldandthenadjusted as
the engine warms up.
Environmental benefits
Fuel injection generally increases engine fuel efficiency. With the improved cylinder-to-cylinder fuel
distributionof multi-pointfuel injection, lessfuel is needed for the same power output (when cylinder-to-
cylinderdistributionvariessignificantly,some cylindersreceive excess fuel as a side effect of ensuring that
all cylinders receive sufficient fuel).
Exhaust emissions are cleaner because the more precise and accurate fuel metering reduces the
concentration of toxic combustion byproducts leaving the engine, and because exhaust cleanup devices
such as the catalytic converter can be optimized to operate more efficiently since the exhaust is of
consistent and predictable composition atomize fuel better. More efficient because, this fuel injection

3. systemoperatessuchthat excessfuel fromthe injectorsisredirectedbacktothe fuel main filter or tank for
recirculation unlike carburetor type where fuel are totally introduced into the combustion chamber and
reliant on the manual settings done on the unit.
SCHEMATICS – ELECTRONIC CONTROLS

4. To highlight more on FI tech bits and pieces; There are two types of FI - open loop and closed loop
systems. Open loop systems have pre-programmed parameters and targets for optimization. If you target
more than 14:1 AFR [Air Fuel Ratio] during WOL (wide open throttle),the air and fuel will be metered and
adjusted toachieve thisaccordinglyregardlessof anyengine rpmorfuel changes.Closedloopsystemsrelies
on an O2 sensor(widebandorsingle-band) monitoringthe exhaustfor real time feedback to the ECU giving
it the capability to range AFR on the fly or in real time. Even if you have a pre-programmed fuel map, it’s
compensatingbecause of the self-adjusting feature. Unless you have your Oxygen sensor welded on your
exhaust pipe, then you have an Open Loop FI, if not then Closed loop is the Motorcycle set up. Either of
these set up makes it more fuel efficient than the carburetor type. There is another variation of the FI but
requiresmore investment, butyouattaina more stable,smooth,friendly ride.Thisfeatureshasthe IAC(idle
air controller), added sensors, better fuel feed ranges or maps, etc.
Note the difference. Most of the FI for MC nowadays uses open loop systems (big bikes equipped with FI
usuallyuse closedloopedFIdesigns).Of course,cheaper,lessparts,lessmaintenance activities, as they say
inits barestformFI. The heart of the FI systemisthe ECU[Engine Control Unit-the computerbox,inlayman’s
term] and most, if not all aftermarket ECU's are fully programmable, while most factory ECU's are not
(unless it's been already hacked by users).
FI some DOs and DON’Ts: Very typical of us to tinker on our priced possessions. More often than not, it
wouldn’tlastaweekor twothat we wouldalteritto our taste like engine upgrades,exhaustsystems,racing
kitslike CDIs.Note thatFI [openloopedsystems],ourengine will stayfuelefficientaslongasthe engine and
peripherals is unaltered. The FI’s ECU are pre-programmed parameters are tuned only to stock parts, and
changingeventhe exhaustsystemdefinitely would affect your overall fuel economy and power. Even just
changingfuel types/octaneratingwill have a direct effect on fuel economy (for better or for worse). Same
goeswithelectrical upgrades. Itwould be interesting to note that FI systems are very sensitive to its input
voltage thataccessorizingitwithany powerhungry item[s] inanFIMotorcycle will have adirecteffectonits
performance. Again, since you’re into dressing it up like installing HIDs, power horns, MP3 boosters and
what have you, then you need to invest on upgrades on your charging system to compensate for these
increase electrical power requirement. Not doing so, will also result to early damage to your ECU and its
related sensors. Worse, if any OEM would check on your unit, such defect on your FI system’s Factory
warranty maybe void.
Your choice,if yougot an FI unitto serve itsrightful purpose of fueleconomyandefficiency then enjoy it to
the fullest.Otherwise,anupgrade lingersinyourvein-youwantmore powerandspeed,be preparedforthe
addedinvestmentthatcomeswithit; lookforclosedloopsystemsto have the best of both worlds (check if
the exhausthave anO2 sensor),upgrade yourelectrical chargingsystem, source hackable ECUsor stickwith
the Carburetor type system. Excerpts taken fr: FB@Sixace.
2] Why manufacturers are slowing turning to EFIs MCs,
With the worldwide clamor for cleaner air emissions as enforced, we’re moving up from UN-ECER 40
Exhaust Emission (Euro 2) in 2012 to the current UN-ECER 40 Exhaust Emission (Euro-3) by 2015 where
World-wide registration started since 2007.
Supersession of carburetors
In the 1970s and 1980s in the US and Japan,the respectivefederal governmentsimposed increasingly strict
exhaustemissionregulations.Duringthattime period,the vastmajorityof gasoline-fueled automobile and
lighttruck enginesdidnotuse fuel injection.Tocomplywiththe new regulations,automobilemanufacturers

5. often made extensive and complex modifications to the engine carburetor(s). While a simple carburetor
system is cheaper to manufacture than a fuel injection system, the more complex carburetor systems
installedonmanyenginesinthe 1970s were muchmore costlythan the earliersimple carburetors. To more
easilycomplywithemissionsregulations,automobile manufacturersbeganinstalling fuel injection systems
in more gasoline engines during the late 1970s.
The openloopfuel injectionsystemshadalreadyimprovedcylinder-to-cylinderfueldistribution and engine
operation over a wide temperature range, but did not offer further scope to sufficient control fuel/air
mixtures,inordertofurtherreduce exhaust emissions. Later Closed loop fuel injection systems improved
the air/fuel mixturecontrol withanexhaustgasoxygensensorandbeganincorporatingacatalyticconverter
to further reduce exhaust emissions.
Fuel injection was phased in through the latter 1970s and 80s at an accelerating rate, with the German,
French,and U.S.markets leadingandthe UK and Commonwealthmarketslaggingsomewhat.Since the early
1990s, almost all gasoline passenger cars sold in first world markets are equipped with electronic fuel
injection (EFI). The carburetor remains in use in developing countries where vehicle emissions are
unregulated and diagnostic and repair infrastructure is sparse. Fuel injection is gradually replacing
carburetorsinthese nationstooas theyadoptemissionregulationsconceptuallysimilar to those in force in
Europe, Japan, Australia, and North America.
Many motorcycles still utilize carbureted engines, though all current high-performance designs have
switchedto EFI. With abovementioned economics and performance, this is paving the way for the shift to
Fuel Injection systems not only in the big bike categories but now on the small to medium sized engine
motorcycles.
3] Is the Aftermarket sales ready for EFI MCs?
LeadingJapanese, other foreign branded motorcycle are currently introducing FI in their small to medium
size engine models. European and US branded big bikes are now mostly equipped with FI. Backed by
technologyfromtheirmothercompanies,theyuse state of the art components that would last them years
[under normal use, unaltered] before major parts replacements are needed. In the meantime, as widely
practiced by these OEMs, their market expansion development strategies comprises of continued
monitoring of sales/area, training of these latest innovations to all major dealers, sub-dealers and major
service centers.Bywayof this,theyestablishMADs[MonthlyAverage Demands] forpartsand consumables
that must be on hand to all these areas. Feedback systems are in place to monitor, control parts demand,
qualityperformance,innovationneeds.These OEMshave theirownrespective Aftersales of Standard parts
or Accessbusinessactivities; these Accessories meet their product standards, and duly certified. A regular
clause in their Warranty policy of their products that only accredited Parts, Service repair and accessories
are to be performed and used.
Aftermarketproducts;abundance isstartingnow,especially with the influx of importations from different
entitieswhocater to replacement, to some extent genuine parts from all over the world, even China. The
onlyhitchisthat, withthe adventof FI technologynow beingintroducedbyleading manufacturers, the use
of these aftermarket parts is an avenue that your unit warranty will be void. Any alteration, installation of
these A/Mparts must bear approval of the Accredited Service Center/Dealer, much worse, approval from
the Factory itself as this pose warranty issue.

6. 4] Are there training centers for individual mechanics so that they will be equipped for FI MCs?
Leading brands thrust to penetrate market starts first with the 3S – Sales, Spare-Parts and Service. Service
activitiesformamajorrole in promotingproducts.Some leadingbrandshave setupDriving,Service training
facilitiestoenhance these product innovations / introduction. Honda has Riding Academy and some other
independentridingschoolsthatinclude training on FIs. They ensure that these products, before any major
salesare done,NetworkssuchasDealers,Service Centersare equippedwiththe know-how onthe products.
Evenindependent parts and service dealers have their own in-house training activities. Leading Technical
Schoolssuchas Don Bosco,SamsonTech to name a few have beenincluding this in their curriculum. TESDA
and other trade schools have short courses on FIs to train our youth on this new technology on top of the
standard automotive technology course on hand.
5] Is it possible for Carb MC to convert to EFIs?
Possible, remember,priorto1950s, gas engine vehicleswere run by carburetor type. A matter of removing
all the installedFIunitanditsperipherals-injectors,sensors,ECU,pluggingall portswhere the sensors were
installed,removal of the high pressure pump, replacing it with the right sized carburetor. Calibrate or fine
tune the carburetor accordingly should do the trick, but this entails tedious activity such as removal of
sensorsinstalledinternallythe engine [suchastemperature,rpmsensor,unlessthishasa feature that it can
be leftthere anddoesn’taffectengine performance;or maybe in the future you would want to return to FI
system], rewiring and some body aesthetic works.
@#nandycerdeniaaturserviz