Carbs vs FI

This is another one of those questions for the ages... This thread idea started in another thread and was starting to spool up! I believe years ago that FI was struggling and now has seem to get pretty damn good! But as well, do we think that FI is the only way to go? Are the carbs of yesterday and today going to be left wasteside for all FI???

I have not had any experience with the FI yet, but can bet that my next bike will be. I have to rip into my carbs soon to do some jetting changes.. At least there's only 2 carbs on my bike :)

after my last experience, or well, my checkbooks experience with carbs, Im willing to try a different route on my next bike.

Man, where are the FI opponents? I already know I hate dealing with the carbs on my bike. Making a freakin' fuel/air mixture change is a farkin' nightmare. FI for me next, unless I hear really good reasons about why it sucks (or blows in this case).

F.I. would be great for Colorado, where one can go from 5K feet to 10K feet in an hour. Took my Honda up Mt. Evans (14K feet) and it ran like crap. The only problems I can see are my carbs run on gravity and F.I needs a fuel pump. Also, my carb will clog-up if it sits for a while. I've read that some injector holes are so small they are made with a lazer. Would they clog up quickly even against the fuel pump pressure?

I dont think carbed bikes are ever gonna go completely away, or atleast not for a long time. They have or had their advantages, but FI is just gonna keep on getting better and better with technology.

F.I. would be great for Colorado, where one can go from 5K feet to 10K feet in an hour. Took my Honda up Mt. Evans (14K feet) and it ran like crap. The only problems I can see are my carbs run on gravity and F.I needs a fuel pump. Also, my carb will clog-up if it sits for a while. I've read that some injector holes are so small they are made with a lazer. Would they clog up quickly even against the fuel pump pressure? Don't hold me to this, but I think Twisty said that even the FI '04 GSXR 1K's had crappy running problems when in the mountains of the GAP and skyway...

FI is a more consistent fuel delivery system. I am sure it will improve as computer controllers get better and more affordable. I do not think all carbs will go the way of buggy whips.

After getting experience with EFI, I have become an evangelist. I friggin hate carbs! I just wish we could get closed loop MPFI!!

Don't hold me to this, but I think Twisty said that even the FI '04 GSXR 1K's had crappy running problems when in the mountains of the GAP and skyway... No! it ran great. But it was low on power. No wheel spin coming out of the corners like normal.

Don't hold me to this, but I think Twisty said that even the FI '04 GSXR 1K's had crappy running problems when in the mountains of the GAP and skyway... ok wrench-heads..please explain why the FI doesnt perform at its peak in higher altitudes. Thanks! :confused:

ok wrench-heads..please explain why the FI doesnt perform at its peak in higher altitudes. Thanks! :confused: Actually, the FI does a much better job of compensating for altitude than carbs (even though CV carbs are somewhat self-compensating). The fact of the matter is that there is less air at higher altitudes and therefore you have less efficient filling of the cylinder on the intake stroke and therefore have less power. Most bikes will run OK at high altitudes, they just make less power than what you are used to. Larry

Think about it, What makes engines work? Oxygen and fuel and a spark. If their is less Oxygen in the air theres less of a combustion. With the carbs the air n fuel dump in together, theres no computer telling it hey theres less oxygen man! With the FI when the comp senses less air moving, it adjusts the fuel. Of course you wont have the same power thats why in colorado cars run slower 1/4 mile times then at sea level. Like Larry sed FI compensates better for the lack of O2, hope that helps at all along with larryg's reply

Actually, the FI does a much better job of compensating for altitude than carbs (even though CV carbs are somewhat self-compensating). The fact of the matter is that there is less air at higher altitudes and therefore you have less efficient filling of the cylinder on the intake stroke and therefore have less power. Most bikes will run OK at high altitudes, they just make less power than what you are used to. Larry I love this guy... :hug:

As soon as bike FI systems improve to catch up with automotive FI systems, many people will be throwing away their carbs and retrofitting FI to their bikes. Also, carbs will disappear completely from production bikes for at least 4 reasons: 1. There will be no need for choking, so you don't have to think how much choke do I need on a 45 degree day, it will occur automatically (like your new GSXR). 2. Overall FI systems can be at least 30% lighter than carb systems. FI using fly by wire (no cable) will be used soon to save even more weight. 3. Fewer number of parts and screws in FI system than carbs. Imagine never having to mess with floats, float needles, bowls, pilot jets, main jets, needles, diaphragms, etc. ever again. 4. Use of an O2 sensor with FI yields maximum fuel mileage, where a carb system cannot lean itself out at constant speed on the highway. FI systems and computers also provide us with more tuning options (accel fuel maps, constant speed fuel maps) than any carb can. Changes to these maps can be made in a fraction of the time it takes to rejet. Also something else to think about with elevation: From sea level to 7500ft you lose about 25% of your engines power and at 15000ft you have only 50% left (SAE standard calculation).

Well, OK! Lighter?? Less parts?? Put down the crack pipe!!! You are WAYYYYYY off!!! I have recently took apart a 954 and never seen so many parts and cables hooked up to a bike. Between the flapper in the airbox and the back pressure valve in the exhaust, there are alot of parts. While the carbs can't adjust like the FI, you can get a carb to give you good milage...but come on!! We aren't looking for milage on a liter sportbike. Also, I share your belief that the carbs will be cast aside for FI as time goes by but don't go puttin down what you don't get. FI is great. The responsiveness, instant power, capablity to adjust to changing climates are the greatest advantages to FI. The same 954 is so sensative and has so much instant power. No carb lag, that is the best part. Now emissions are another plus but I could care less about that so I'm not even going to worry about that...

GIXXER.COM has the emission block off plates for my 04. I will be installing them soon.

The FI systems on bikes are very similar to the early fuel injection found on cars in the 60s, corvettes for example. They were overly elaborate and clunky systems. 40 years later they have been reduced to a mass air meter, butterflies, injectors, and assorted sensors. Given time, FI technology will catch up on bikes to the same level as today's cars. As a design engineer, I have some sketches of FI systems for bikes that use half the number of parts as a set of carburetors. Again, over time, FI has a great potential to reduce the size, weight, and complexity of fuel systems on bikes. Remember that when cars began using fuel injection, bikes werent even liquid cooled yet. Only recently has the sport market become large enough to fund more R+D to push the limits of motorcycle technology.

I am totally for that FI systems are better in many ways, but while they may have less parts at the thottlebodies but they are very involved in many other ways.... But your point about the level of technology is the reason why I didn't buy a FI bike 2 - 3 years ago....now Twisty's GSXR has a nice FI system...

Yes it is great compared to my TL. No hickupsat all.

The 954 is really nice but just used yours for the better example...expecially sense we have already been talking about it..

My 2000 TLR's FI is quite primitive in the low revs (stumbles sometimes). Any mods that can help this out?

Yes sir. There is a thing called a TRE here is the link. I put it on all my babies. http://www.ivansperformanceproducts.com/tre.htm

Think about it, What makes engines work? Oxygen and fuel and a spark. If their is less Oxygen in the air theres less of a combustion. With the carbs the air n fuel dump in together, theres no computer telling it hey theres less oxygen man! With the FI when the comp senses less air moving, it adjusts the fuel. Of course you wont have the same power thats why in colorado cars run slower 1/4 mile times then at sea level. Like Larry sed FI compensates better for the lack of O2, hope that helps at all along with larryg's reply Well, technically, CV carbs found on most street motorcycles do compensate for changes in elevation because the fuel mixture is dictated by pressure differentials within the carbs. The amount of fuel drawn out of the float bowls is proportional to the amount of air passing through the venturi so less air = less fuel. However, it still isn't as accurate as EFI and you are still dealing with the power loss associated with having less air. Larry

My 2000 TLR's FI is quite primitive in the low revs (stumbles sometimes). Any mods that can help this out? The TRE tricks the ignition box into not retarding the timing in lower gears. However, I think you are referring to how sensitive the throttle input is on the early Suzuki EFI bikes. The slightest throttle application results in a very jerky reaction. In fact, that was a big problem on the track because it was hard to get a smooth drive out of corners and guys were highsiding like crazy. If you remember, Yoshimura Suzuki even ran year old models so they could continue to run carbureted bikes while developing a better fuel injection system. Anyway, the trick I found on these was to adjust the the low throttle position to a richer setting to soften the reaction. It did a pretty good job taking the edge off and most guys preferred it that way. Larry

Anyway, the trick I found on these was to adjust the the low throttle position to a richer setting to soften the reaction. It did a pretty good job taking the edge off and most guys preferred it that way. Larry I don't have a TLR or F.I., but I'm curious as to how this is done. Also curious about what adjustments can be made to a F.I. without getting into the computer. Or is the low throttle position done in the computer?

Thank you Larry for putting the score back to somewhat more respectable for carbs... Carbs 3 FI 5

I don't have a TLR or F.I., but I'm curious as to how this is done. Also curious about what adjustments can be made to a F.I. without getting into the computer. Or is the low throttle position done in the computer? When I was doing that, it was with the Yosh box. This was before the PowerCommanders and Yosh EMS systems were out and brake dynos were just entering the motorcycle market. Yosh made a programming box where you set knobs for throttle position, rpm, and +/- fuel (IIRC). You set the dials and then reflashed the OEM ECU with this setup. We used to throw in a little more fuel (+10% or so) for the low throttle position at all rpm to help soften the jerkiness. In effect, we were taking the edge off of how crisp the throttle response was. Larry

Thank you Larry for putting the score back to somewhat more respectable for carbs... Carbs 3 FI 5 Hey man, I like carbs, I'm going to be one of the few techs around that know how to work on them. Those skills even helped me sort out the carbs on a 1967 Honda S600 convertible (car). Larry

Yeah...Larry rocks!!

CARB is going to require ALL Vehicles to be Fuel injected by 2008 so i htink you may see a few bikes no longer sold in CA but most all of em will get the injection treatment by the 08 model year, if they dont get it itll be a bike u cant register in CA or the Co will just discontinue the model... hopefully that doenst mean some bikes like the EX500 and GS500 get dumped.

Hey man, I like carbs, I'm going to be one of the few techs around that know how to work on them. Those skills even helped me sort out the carbs on a 1967 Honda S600 convertible (car). Larry FI needs a battery/power source to run the pump to pressure the rail. Carbs use gravity and Venturi What happens when your battery only has enough power to light your bike but you have to push it to start it? The guy with the carbs will have to send the truck back for the FI bike.

Good Point Bee on the carb guy bike running with minimal batt power!!

FI needs a battery/power source to run the pump to pressure the rail. Carbs use gravity and Venturi What happens when your battery only has enough power to light your bike but you have to push it to start it? The guy with the carbs will have to send the truck back for the FI bike. Nice try but a lot of carb bikes still need fuel pumps. If the fuel outlet on the tank is below the carbs, you need a pump to get the fuel up to the carbs...gravity ain't gonna save you there :D The bigger issue is whether you have enough battery to run the ignition box...and that affects all kinds of bikes. Larry

Since FI needs a computer, how come it doesn't crash as often as home computers? Some computer-controlled cars had a "limp home mode" or something where the computer had to relearn where to set the timing and other settings if the battery was disconnected. Does this happen with bikes? I like my carbs and I'm sticking with them. They are just simple mechanical machines and easy to clean. If I have a problem on my bike it almost always seems to be electrical. And if I have a problem at home, it's almost always the computer. If a FI bike won't run, good luck fixing it in Hanksville, UT (going through there next spring).

Very good point there Worries...that was the logic in my thought process when I purchased my bike in '02! However, the newer FI's are alot nicer and don't have near the glitches that the old ones did. Take for example Twisty's '04 GSXR 1K...it has a great FI system that runs a great deal better than the old ones. Another thing to think about is...Would you go to your respective car dealership and say please show me the cars you have in carberators and not FI?.....I think not, but yet you will carry your family in these and think twice about it. Heck, I'll go out on a limb and say you would never want to buy a everyday driver (car) without FI!!!

No problems with my FI

Since FI needs a computer, how come it doesn't crash as often as home computers? Some computer-controlled cars had a "limp home mode" or something where the computer had to relearn where to set the timing and other settings if the battery was disconnected. Does this happen with bikes? I like my carbs and I'm sticking with them. They are just simple mechanical machines and easy to clean. If I have a problem on my bike it almost always seems to be electrical. And if I have a problem at home, it's almost always the computer. If a FI bike won't run, good luck fixing it in Hanksville, UT (going through there next spring). If you prefer more time riding than tuning FI is way to go ;) FI bikes make more power, better milage, better emissions, better cold running plus add aftermarket pipe no jets to screw with. Newer FI bikes are extremely reliable, BMW forums you never see problems posted from FI. FI has more parts but many of them are non adjustable or electronic modules Limp mode FI simply reverts back to running as inefficently as carburetor :lol: Another problem with carbs, everybody monkeys with them f@cking them up :lol:

Carbs will be evetually gone... and the Date is by 2008. There will not be a new bike sold in the state of California at that date... and if u buy a 08/09 elsewhere and move to Cali... u cant register it there, it will be a non streetlegal vehicle for off road/race use only in Cali.