[FullRangeMan]

Iam in doubt.
What is your preference?
Why?

[mcgsxr]

I voted for FI.  Especially if i am not going to have to work on it.

If I have to bring tools under the hood, it better be a carb, or I won't touch anything!

All my bikes were carbs, so I have some experience working on those.  I have never touched a fuelie motor, I know nothing about those systems.

[steve f]

Fuel injection especially in bikes.

[Scott F.]

Carb...old school...I know them and can work on them just like a distributor with points and a condenser. Give me a screwdriver, a file and a matchbook and I can make it run (assuming something major isn't broke like a timing chain).

All that computer driven stuff is cool, makes the vehicle get better mileage, perform better, all that positive stuff....but when it breaks, I have to spend money with a 3rd party mechanic who has a computer to diagnose the problems. Just isn't that way when you go old school, providing you understand internal combustion engines.

...that's just me though, sometimes I think I was born with a wrench in my hand

[Peter J]

FI has gotten pretty trouble free in recent years. One could be pretty care free about it if  buying within the last few model years.

 I kinda get where the carb thinking comes from, but FI is essentially the same thing with more far more accurate control systems.  Electronic engine controls get blamed for way more troubles than they actually create because of the perceived voodoo in the black box. They rarely fail. They cost more because there's more engineering involved.

 Far more computing power in most phones than it takes to manage a fuel and ignition system.

Can you tell which camp I'm in?

Vintage is a different story...

[SteveFord]

Either is fine with me.
Carbs never run exactly perfectly but they get close enough.
FI is more complex but I've got a laptop and the necessary programs, cables and training to do the work myself.
Fuel injected bikes can be made to run perfectly but there's also a whole lot more to screw up on you.

[FullRangeMan]

Thanks all for yours replies.
I have asked it because a famous local vintage car restorer prefer carburetors why according him FI boards and car electronics in general last only 15 years in use or not.

[SteveFord]

As me in 3 years, I use a fuel injected 2002 Buell every day. 
I haven't heard of any of this stuff having a shelf life. 

[simoon]

Not to change the subject...

Rotary engines LOVE carburetors!

The only thing limiting the RPM of a rotary engine, is the amount of gas you can get into the combustion chamber. The rotor will just keep spinning faster and faster. 

Unlike piston engines, with their RPM limiting valve lag and valve float, rotaries are not limited in RPM because there are no valves to lag. Just keep feeding a rotary more gas, and the RPM will continue to increase until the seals blow, or the engine seizes. 


I once had a pretty beat up looking '84 RX7 with an (illegal) side draft carb, headers (also illegal) that would literally blow away Porche 911 tubos. I would leave them at the light like they were standing still and dumbfounded. Not even close.

The power to weight ratio was off the charts. 1800 pound, car with an engine capable of ridiculous RPM.

The car was a real death trap, though. The aerodynamics were not good enough for that kind of speed. I once (and only once) pegged the speedometer at 135 (and the speed kept climbing), but the front end felt like it was getting airborne. I saw my life passing before my eyes, and as quickly as I could, got the car below 80.

Sold it a week later.

[FullRangeMan]

Seems it was the Wankel engine.
This kind of motor suffer from a lack of torque?

[Peter J]

You got it FRM, rotaries do (did) suffer from a lack of bottom end torque, but they smoothly sailed way up in RPM, at one time unmatched by any reliable piston engine. Very small and light for the HP produced. Development and evolution of higher revving piston engines have kinda eclipsed them now though. Too bad, I had several. I appreciate that Mazda developed as far as they did, but even the most tenacious have to admit an uphill battle and they became more of a novelty than a contender.
   

What simoon describes is actually true of any internal combustion engine. I best heard it described as an ill-conceived air pump. More air in and out = more horsepower. With rotaries, the only real way to open up the exhaust in a big way was with peripheral porting, which had some not so good effects; more loss of torque and heat... serious heat. They breath fire, exhaust temps reaching 1800° or more. It also made them dirtier emission-wise.

They still find homes in a variety of racing, but alas, we may have seen the last of them for street. I have read rumors that they'll resurface, who knows.

As you can see, I've done my best to take this on a tangent, so I'll retreat.

[FullRangeMan]

The 1970s C111 sound like a V8 but two rotors.
https://www.youtube.com/watch?v=6J1eZ65SgkE

[Peter J]

Didn't know about the Merc. The rotary found it's way into some strange places. I actually worked on one of these once upon a time.

https://www.youtube.com/watch?v=7vslAzwfz90

That's not me in video, BTW 

[Johnny2Bad]

Carbs work well and produce great power, FI's advantage is more about timing and precision of combustion events than fuel delivery (most will waste fuel at idle, cold motor, or WIde Open Throttle (WOT) conditions, for example).

The Engine Management Computer just happens to work well with injectors but you could map the fuel curve of a carb and the EMC could perform all it's other magic with all of the benefits (eg: Variable Valve Timing control).

When it comes to cost, there is a huge gap between the two systems. A High Performance carb & manifold for a Small Block Chevy (SBC) motor might run you $600, add in a General Motors High Energy Ignition system for $150, you're done and peak power is the same as your aftermarket EFI system at $thousands ($2K is getting away cheap).

GM still sells the 350 SBC-based truck motor, brand new (not a rebuild) for under $2,000. You need a roller cam for $400 to bring performance up.

You can get a 700R4 auto transmission (3+OD) one of the strongest units out there, no computer needed, stronger than stock (450 ft/lb capacity) re-manufacture, under $1500.

Now, find me a 300+ HP SBC and 4-speed auto for around $4500 in a Fuel Injected version. Good Luck with that.

Plus, I like to kick-start my bike. Normal Programming on a FI ECM is to not fire the plugs until the 3rd spin of the power stroke. I'm man enough to admit my leg isn't that strong.

[FullRangeMan]

Didn't know about the Merc. The rotary found it's way into some strange places. I actually worked on one of these once upon a time.

https://www.youtube.com/watch?v=7vslAzwfz90

That's not me in video, BTW 

Incredible, in the 80 I wa in love w/Suzuki bike wankel:
https://www.youtube.com/watch?v=4h93bel8MOc

[Johnny2Bad]

The 1970s C111 sound like a V8 but two rotors.
https://www.youtube.com/watch?v=6J1eZ65SgkE

Wow, what a cool series of cars. Thanks for putting them on my radar.

You should kick my ass for what follows, but M-B says C111-I (1969) was 3-rotor and C111-II (1970) was 4-rotor. Off I go now searching for more on this amazing ride.

Thanks again.

[FullRangeMan]

Thanks for inform Johnny, looks the balanced exaust note was a 3 rotor on that video.

[Tubeburner]

The new factory hot rods are producing lots of horsepower these days. Old school likes carburators, but they can be a pain. I spent time on a high altitude dynamometer tweaking carburetors and it was not easy. Now drive the same car to sea level and it runs too lean. The fuel injection of today is fast and does amazing things.

The old saying at the race track: Injection is nice, but I'd rather be blown!

[Johnny2Bad]

The new factory hot rods are producing lots of horsepower these days. Old school likes carburators, but they can be a pain. I spent time on a high altitude dynamometer tweaking carburetors and it was not easy. Now drive the same car to sea level and it runs too lean. The fuel injection of today is fast and does amazing things.

The old saying at the race track: Injection is nice, but I'd rather be blown!

Undoubtebly computer-controlled FI makes altitude compensation easy but there is such a thing as automatic altitude compensation in some carb designs. Plus, with your experience on the dyno you could do what experienced mechanics of the day did ... Pulled out the screwdriver, fwisted a screw a quarter turn, and carried on.

[Tubeburner]

I wish it was that easy. To make a Shelby GT350 or GT500 come out of a corner, we had to reduce the enrichment circuit of the Holley carbs, change jets, power valves and sometimes modify air bleeds. We preferred not to damage a factory Holley, so we inserted wire in passages to reduce their size. The screw you mention is strictly the idle circuit and will not enrich the rest of the carburetor. Most people just bolt on a carburetor and never use a dyno and gas analyzer to truly set it up. We set up some Mustang SVO 4 cylinder turbo and back then we used a boost switch and a resistor from Rat Shack from the boost switch to the fuel injection enrichment to make it see a lean condition so it would richen up the injectors. Now we have multiple oxygen sensors, fast ECM's and programers to get what we want. I love the old and the new. The new is getting exciting with all the recent HP gains.