Carbureted or Fuel Injection

jixerking

jixerking

New Member
A guy walks into a store and says " im looking for my first trackbike", and the clerk says "u want carburetion or fuel injection??", then he says "well whats the difference?" so the clerk frowns and says "hell if i know, Y dont u ask those NESBA guys the pros and cons?" can somebody help him????:popcorn::popcorn:
 
Demps

Demps

New Member
I have never had a fuel injected bike, but I think the main selling point for a new track day enthusiast to get a fuel injected bike is the reliability. The fuel delivery system is simply better and much more precise. This leads to quick and reliable starting and very steady operation. Obvioulsy there are many more pros for fuel injected bikes if you want to start making power improvements, like a power commander with custom injection maps.

However, I have a 99 R6 track bike that is carbureted. I have never had a problem starting. Starts first couple turns everytime during the season. The first start after the winter lay off is always rough, but she always gets going.

Bottom line, F.I. bikes are more reliable, but carb bikes can work just fine in they are well maintained.

Just my 2 cents.
 
B

beechkingd

Member
Well tuned carb engines are smoother while in maintenance throttle then FI engines are. FI engines are less of a black art to tune, make way more power and are easier to start then carb engines. I really don't see normal CV carbs requiring much more maintenance then FI bikes. Although, flat slide style carbs on the other hand are a totally different animal and do require lots of constant setup. If you get garbage in the fuel system of a FI or carbed bike you will have problems and neither of them tolerate being neglected or parked for years.
 
ctrank

ctrank

Member
My first track day bike had carbs. Other than being a little cold blooded on those cool mornings at the track, I didn't have any issues with the bike. In fact, it ran like a champ!

For a beginner, an older bike with carbs certainly wouldn't be a bad thing. What I think is good about carbs is that they don't respond as quickly to throttle input changes as the newer modern FI bikes do. This translates to smoother power delivery and a lower probability that grabbing a handful of throttle at the wrong time mid corner will put enough power to the ground to cause a problem. FI can work more like an "on/off" switch, where as carbs respond more like a "dimmer" switch which helps new riders develop the essential skill of being "smooth" with the throttle.

If none of that made sense, recommend a 2009 R1 and be done with it. :bumpme:
 
rk97

rk97

Member
the only thing i don't like about carbs is cleaning, synching, and tuning them...

but they probably are BETTER for a beginner. That video someone posted from B group on sunday, where the rider grabs too much throttle in turn 5 on thunderbolt - i bet he had FI. that's not to say you can just whack open the throttle with impunity if your bike is carbureted, but try it in the pits, and compare to a friend's FI bike.

if you go from idle to WOT with carbs, the bike hesitates, and almost 'chokes' on the massive influx of fuel. Choke might not be the best word, but it's the best i can think of.

an FI bike has no similar hesitation. the response is immediate.

ON TRACK, there's no meaningful difference at our skill level. If yuo're being smooth on the throttle, the carb hesitation shouldn't matter much, if at all.

that said - for emissions purposes, all new bikes will be FI soon. I was kind of surprised the 2008 ninja 250 wasn't. The EX500 and ZZR600 were discontinued rather than being upgraded to carbureted engines. The Katana is gone in favor of the GSXF 650, and so on. FI has come down in cost almost as fast as flat-screen TVs :p
 
rk97

rk97

Member
can someone explain the mechanical difference? I mean, i know that carburetors use an air/fuel mixture based on the size of the jets, and how far you turn in/out the pilot screw; and FI actually sprays fuel into the engine - but that's about the extent of my knowledge...
 
Joe Vital

Joe Vital

Member
carbs are metered by brass jets as you stated. there are (typically) three different circuits for the fuel, low speed, mid-range, and wide open throttle (WOT). each circcuit has a seperate jet, the pilot for low speed, needle for mid range, and the main for WOT. one tunes the carbs by rejetting each circuit.

eletronic fuel injection is metered by an engine control unit (ECU). the ECU take readings from various different sensors, air temp, air mass, engine speed are the basic ones. these readings then dictate what the ECU 'tells' the injectors to do. the injectors get a signal from the ECU to spray fuel for some amount of time depenfing on what the sensors and ECU determines to be the 'correct' amount. these 'correct' values are found in the map the ECU uses to control the injectors. one tunes the EFI by remapping the ECU.

the above is only meant to be a cartoon of what is happening. hope this helps.
 
Joe Vital

Joe Vital

Member
oh yeah...the mechanical difference...carbs use vacuum to draw the fuel out of a reservoir of fuel-the float bowl.

EFI uses pressure from a fuel pump.
 
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