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Fuel Injection for the FCR carb?

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Posted by: Chili---------------------

Would be curious to hear your thoughts Rich and 89'r as well as any others qualified to comment on this technology.

http://www.racerxcanada.com/breakin...r-the-fcr-carb/


Posted by: _JOE_---------------------

I'm interested. Almost sounds like a logical solution for those too, shall I say...lazy, to change the leak jet.


Posted by: whenfoxforks-ruled---------------------

It will definitely speed leak adjustments! And in my opinion,is thee source of off idle bog,generally fixed by putting a 70 or 75 in. These guys are gonna sell a lot of them! Set properly,you do not need the choke or hot start to bring it alive,just kick!


Posted by: 2 strokes for life---------------------

Chili, thats some cool new tecnology they are coming out with but proper jetting is a bit cheaper. But i could not make it so good on them.


Posted by: Spokes574---------------------

FI will be more cost and more reliability concern.
The main push for FI is that it lowers the exhaust sound.
That's right. It lowers it about 2-3 db. Given that the sound
requirement will be tighter in the future, the only ways to keep power up
and sound down is to use FI.

If FI is not used, to reduce sound the muffler will have to be choked
which lowers the power.

So that is the real reason for the FI push.
As for me. My CRF is jetted perfectly and changing a jet when temp. gets
to around 85+ is cheap and easy. I will not purchase a new bike just for FI.
There will have to be more - new engine or new frame.

Spokes574


Posted by: Rich Rohrich---------------------

Quote:
Originally Posted by Spokes574
FI will be more cost and more reliability concern.
The main push for FI is that it lowers the exhaust sound.
That's right. It lowers it about 2-3 db.


Care to explain?


Posted by: Filthy_McNasty---------------------

Quote:
Originally Posted by Spokes574
FI will be more cost and more reliability concern.
Since the FCR carb costs around $800, I doubt that fuel injection will be much more epensive. And FI has been refined to the point of trouble-free operation in both automobiles and street bikes. When's the last time your fuel injection system in your car broke?


Quote:
The main push for FI is that it lowers the exhaust sound.
That's right. It lowers it about 2-3 db. Given that the sound
requirement will be tighter in the future, the only ways to keep power up
and sound down is to use FI.

If FI is not used, to reduce sound the muffler will have to be choked
which lowers the power.
You're looking at it through the wrong end of the telescope. FI does not lower sound output. The manufacturers are going to have to resort to more restrictive exhaust systems to tame sound, and fuel injection will allow the engines to more easily retain good performance and response with the increased restriction than a carburetor.

Quote:
I will not purchase a new bike just for FI.
On that we agree. I have no problems with EFI, but carbs work just fine for me too. FI by itself is not enough reason to buy a new bike.


Posted by: kylee---------------------

Quote:
Originally Posted by whenfoxforks-ruled
It will definitely speed leak adjustments! And in my opinion,is thee source of off idle bog,generally fixed by putting a 70 or 75 in. These guys are gonna sell a lot of them! Set properly,you do not need the choke or hot start to bring it alive,just kick!


Couple of questions. I'm EXTREMELY ignorant of this topic, so hope you can clarify several sticking points for me.


None the less:

2.) These do not require significant electronics to provide feedback on flow? Why is that?

Quote:
Originally Posted by Filthy_McNasty
Since the FCR carb costs around $800, I doubt that fuel injection will be much more epensive. And FI has been refined to the point of trouble-free operation in both automobiles and street bikes. When's the last time your fuel injection system in your car broke?


3.) Isn't the technology in the article an aftermarket add-on to modify the FCR carb as opposed to an integrated FI/EFI system?

My apologies for the level of ignorance implicit in these questions. I am just trying to learn. Thank you in advance.


Posted by: Ol'89r---------------------

Quote:
Originally Posted by Chili
Would be curious to hear your thoughts Rich and 89'r as well as any others qualified to comment on this technology.



Doug.

I have no personal experience with it other than what I have read about it. Sounds like a good idea if one races at different altitudes. Would save a lot of time from having to change your leak jet.

Spokes574.

This has nothing to do with EFI. The EFI is only being used as a catch phrase for advertising. Kinda like global warming.


Posted by: Rich Rohrich---------------------

Quote:
Originally Posted by Filthy_McNasty
Since the FCR carb costs around $800, I doubt that fuel injection will be much more epensive.




The high end retail price of a 40mm FCR is less than $600 (CARBURETOR ASSY. (FCR00D A) 1 $576.73 )

This puts the OEM cost well below $300. Those prices only exist because the FCR is used across so many models and manufacturers and it hasn't changed significantly in a few years. Average cost and the resultant OEM prices are directly related to that.

It will take years for a similar "shaking out" to occur with EFI, assuming it ever does.

These are vastly different systems than the EFI under the hood of our cars. While Honda has had great results so far running a no-battery EFI system on their production four-stroke 250 trials bikes, it's still too early to know what problems will be lurking for us down the road once EFI is introduced.

Once thing is for sure it will cost the OEMs a lot more money to implement and there will be problems associated with it. The extent that those costs are passed on to us remains to be seen.

It looks like interesting times are ahead.


Posted by: Rich Rohrich---------------------

Quote:
Originally Posted by Chili
Would be curious to hear your thoughts Rich and 89'r as well as any others qualified to comment on this technology.



Doug - Assuming it's engineered correctly I don't see why it wouldn't accomplish the task. The bigger question for me would be is it really useful?

What I'm getting at is the differences between tuning for the atmospheric conditions, the evaporization characteristics of the fuel, the track conditions, and the riders "style".

I have to go do some stuff but I'll be back later tonight. In the mean time think about what influences the "tuning" of that accelerator pump shot.


Here's a few thoughts to ponder on fuel requirements in a four-stroke.


Regardless of engine speed, the airflow and fuel delivery demands of the engine depend on the load being placed upon it. That load and the resulting throttle opening directly effect manifold pressure (MAP), which in turn affects the fuel requirements.

MAP increases as load and power increase

Fuel requirements depend more than anything else on how much work you are asking the engine to do, basically how much of a load you are placing on it.

As the throttle opens to atmospheric pressure manifold pressure (MAP) increases.

Pressure in the intake depends on throttle opening, and cylinder filling (VE) is directly tied to throttle opening.

The pressure differential in the fuel metering system of a carburetor is usually pretty small, only a few pounds per square inch (PSI), but it's that differential pressure that forces fuel through the jets in the carb. As the pressure differential changes so does the amount of fuel passing through the jets into the engine.

The only circuit that ignores the pressure differentials and relies solely on fixed mechanical methods to introduce fuel is the AP circuit.


I'll be back later and we can chat about why this matters.


Posted by: Ol'89r---------------------

[QUOTE=Rich Rohrich]Doug - Assuming it's engineered correctly I don't see why it wouldn't accomplish the task. The bigger question for me would be is it really useful?
QUOTE]

Rich.

I can see where it would be useful in an area like California where we race at sea level one weekend and then go up to 6,000 to 9,000 feet another.

I believe all it does is eliminate the leak jet or use the largest leak jet avalilable and allow you to meter the leak jet circuit without taking the carb apart. Of course, drastic altitude changes may require the changing of other jets and you may have to take the carb apart anyway. I don't think it would affect other areas of carburation since the AP circuit is an entirely different circuit than the other jets.

Proper adjustment may be interesting and difficult to find but once you figure it out for different altitudes and tracks, you could keep a chart to tell you how many turns out to adjust it for specific altitudes.


Posted by: kylee---------------------

Quote:
Originally Posted by Rich Rohrich
I'll be back later and we can chat about why this matters.


Okay? So did ol89 cover this or is there more?


Posted by: whenfoxforks-ruled---------------------

I did not catch the fi before,this has absolutely nothing to do with fi,its a diaphragm mod to facilitate an adjustable leak jet. I do not have personal issues with needing to change the leak jet as often as the rest! But when I do,the 250f is a real pain to change that jey!



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