Why would anyone in their right minds want EFI? I work on quads and the ones with EFI are a right pain. If anything goes wrong with the system it costs a fortune to put right and diagnosing faults is a nightmare. They don't produce more power, in theory they can produce either more power for the same fuel consumption or better economy for the same power, but VW's troubles suggest this is largely on paper, rather than any real world advantage. Air pollution regulations has led to the adoption of EFI in cars, hardly a problem where Quads are used.

 

If people had to work on them on a daily basis as we have merryman they'd see what you mean. Keep the old carb models running while you can as it wont be long before you can't buy a new carb model atv.Even the youth models are slowly turning to efi and carburetors are becoming extinct just like the dinosaur.

 

Can't say that you are wrong. But I know that there is some power loss at the elevations I ride at with Carbs. I haven't had any trouble with EFI yet....other than being slightly cold natured for the first minute or so. Until I do, I'll ride it like I stole it.

 

Carbs for the most part are fine. They do require you to pull the choke out and take a couple minutes to start and idle but I guess that's really no big deal. Efi may not make more power but it does give faster throttle response and is less affected by altitude. As OPT said, almost all the new models coming out now have efi, save a few youth and economy models. EPS was something nobody would have considered on a quad or utv 10 years ago either. I guess we just get spoiled by technology. But yes, if a quad has problems with its efi system I'm sure it will cost a lot more to fix than rebuilding a carb. That's just part of the deal but it doesn't stop people from buying new efi and eps equipped quads. I'm sure eps would be very expensive to fix as well if it needs servicing.

 

As mentioned by a few and my main reason is altitude. It is rare I ride below 9000 ft elevation, heck I even live at 8000 ft. Trails I go on are over 12,000 ft. That does not mean because I have FI that I do not lose power because I certainly do. I also run a FI controller though.

Both my performance car and truck are FI and turbo'd and I wouldn't want anything different. I do understand most do not live at altitude... but for me having an option to not run a carb is greatly preferred.

 

I doubt if the EFI systems on Quads will cure altitude sickness, in fact, on most you can't alter the fuel air ratio manually so they may be worse. Proper fuel injection systems have an oxygen sensor in the exhaust to give the correct fuel/air ratio all the time. I haven't come across any Quad with one of these. Quads have sensors for temperature, manifold vacuum and throttle position, I can't see any way this would detect air pressure and compensate for this. By the way, Suzuki EFI 400s and 450s have choke levers.

 

Only efi machines we had in the shop with oxygen sensors were Husqvarna,Ktm,Motoguzzi,Ducati on and off road models. Haven't seen a quad with one yet,but possible some are out there. Why you have to wait on touching the throttle on an efi atv when it's cold is because the computer goes into what's called a "waste spark,waste fuel" management mode for protection until it receives input from the tbap,tps,air temp sensors and adjusts fuel and air accordingly. That's why so many people fouled out plugs on many of the early ones when they became impatient and gassed the throttles. Oxygen sensor equipped machines cost more in manufacturing,etc so that may be part of the reasoning.If they ever do go to oxygen sensors then you would see a marked improvement on warm up time and possibly on fuel mileage also.

 

I rode few EFI machines and even a 500 Sportsman with efi and notice zero throttle response difference. As for altitude I think before a carb model would puke you would need to be pretty high.
I run the top of our local ski hill and did not notice anything but its only 1500ft. Pretty well nothing in the entire province Ontario Canada is over 2000ft so that EFI advantage would never come into play.

I like the carb advantage that it can be pull started with a dead battery , not sure a EFI can do that?

My new 2012 800-etec snowmobile is EFI and besides not needing to choke it on a cold morning start up it behaves like my previous carb sleds.
Infact I rode another 2012 Ski-Doo 800R Renegade that's a pull start model only with TMS carbs rather then Direct Fuel Injection like mine and I could not tell them apart.


As for the question "what is most reliable brand" ? If I went buy older ATVs still running around I would say ,Suzuki, Honda and Yamaha . I see a lot of late 1980s of those still on the trails.

 

Direct from the Yamaha Service Manual for the 2007 Grizzly 700


Sure, not as exact as an oxygen sensor in the exhaust, but I'm pretty sure the Pressure Sensor is there for something related to fueling adjustment. Just a guess


So similar to what OPT posted about the tbap and temp sensors used to calculate how to adjust fueling. Is it extremely efficient? Probably not. Do I have to change a jet when I go to lower elevations with my EFI? No. If you haven't had experience at altitude with EFI, don't be so negative until you have tried it.

 

Sorta close as the t-bap does exactly as it's called. Measures the outside temp and barometric air pressure,but the oxygen sensor goes straight for the heart of the engine and measures what the engine is outputting into the exhaust and adjusts fuel to air ratio more precisely. An engine can run cleaner,leaner and make more efficient use of the fuel.I'm just hanging around to see if they're going to require some sort of catalytic converter next.The blame things cost enough as it is for autos if you ever have to replace one. Think some street bikes may already have them.