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V-Twin Moddin
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Discussion Starter · #1 ·
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???
 

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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 :)
 

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

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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).
 

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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?
 

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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.
 

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V-Twin Moddin
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Discussion Starter · #7 ·
No Worries said:
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...
 

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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.
 

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Gas Man said:
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:
 

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Need4Speed750 said:
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
 

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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
 

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larryg said:
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:
 

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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).
 

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V-Twin Moddin
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Discussion Starter · #16 ·
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...
 

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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.
 

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V-Twin Moddin
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Discussion Starter · #19 ·
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...
 
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