Carb to EFI Less Power?

[WhipLash96]

OK, I am in the midst of converting my Road Glide to EFI. In talking with my engine builder he flat out said that there is a big possibility that be switching from a carb to EFI with the exact same set up that I could lose power instead of gain. Does this make sense to anyone? It certainly defies logic for me, but what do you think?

[HogMike]

OK, I am in the midst of converting my Road Glide to EFI. In talking with my engine builder he flat out said that there is a big possibility that be switching from a carb to EFI with the exact same set up that I could lose power instead of gain. Does this make sense to anyone? It certainly defies logic for me, but what do you think?

Ask him to explain how.
I don't see it.

[WhipLash96]

OK, I am in the midst of converting my Road Glide to EFI. In talking with my engine builder he flat out said that there is a big possibility that be switching from a carb to EFI with the exact same set up that I could lose power instead of gain. Does this make sense to anyone? It certainly defies logic for me, but what do you think?

Ask him to explain how.
I don't see it.

His very vague response to the "Why" question was in the way that carb atomizes fuel vs. EFI.....  I was looking  more but that is all I got....

[PoorUB]

I don't see it either. With EFI you can tune for RPM and throttle position, or MAP depending on the year. With a carb you have idle, mid and full throttle jets. Fuel required at full throttle and 3,000 RPM may be slightly off from full throttle and 5,000 RPM. A well tuned carb does a decent job, but you can tune an EFI tighter. Plus an injector does a darned nice job of atomizing fuel, better than a carb, IMO.

The guy is old school, probably likes breaker points too.

[Norton Commando]

I don't see it either. With EFI you can tune for RPM and throttle position, or MAP depending on the year. With a carb you have idle, mid and full throttle jets. Fuel required at full throttle and 3,000 RPM may be slightly off from full throttle and 5,000 RPM. A well tuned carb does a decent job, but you can tune an EFI tighter. Plus an injector does a darned nice job of atomizing fuel, better than a carb, IMO.

The guy is old school, probably likes breaker points too.

[smoserx1]

Well I know this is not what you are planning but remember the 99-01 baggers that had the MM-EFI?  They all had 3.37 ratio primaries and I heard somewhere that was because they made less torque than their carb brothers.  So your builder said it was a "possibility."  He didn't say it would actually happen, but the conversion would add a layer of complexity that I don't see unless you just can't get a carb to run properly on your bike.  My bike has a carburetor (and it runs good) and I wouldn't even consider it but I am very much an "if it ain't broke don't fix it" person.

[Hossamania]

I would think that if the efi system is set up to match the build, power should not be a problem, and it should run a little smoother than a carb.

[HogMike]

OK, I am in the midst of converting my Road Glide to EFI. In talking with my engine builder he flat out said that there is a big possibility that be switching from a carb to EFI with the exact same set up that I could lose power instead of gain. Does this make sense to anyone? It certainly defies logic for me, but what do you think?

Ask him to explain how.
I don't see it.

His very vague response to the "Why" question was in the way that carb atomizes fuel vs. EFI.....  I was looking  more but that is all I got....

In his defense, I have a 2019 with EFI that runs verrrrry nice (after a good dyno tune) BUT my other 3 bikes have carbs.
All the bikes run very well with the EFI bike getting a little better gas mileage. Only difference is the other bikes have choke knobs! I'm NOT going to change the carb on them. Ride ability on all the bikes are just fine, no hiccups stalls or hard starting on any of them.

No need to "fix them until they break".  My son's crew chief has THAT motto on his shop wall.

[Ohio HD]

It only makes sense because he probbaly has no clue as to how to program and tune FI bikes.     

[kd]

I did a quick search on carb / EFI power differences.  In the race world they go both ways.  The carb seems to get the more power at full throttle refit over EFI but that's specifically WFO.  EFI can be quickly adjusted to barometric, temp, altitude and other conditions and carb not so much.  Closed loop EFI can be helpful to keep up on changing conditions.  Carb, you need tools and a pocket full of parts. Look at what your building it for and your expectations.  A good tuner can do wonders.

[Don D]

All things being optimally configured he is 100% wrong

[rigidthumper]

A carb requires air movement to express fuel, and the slower the air speed, the more likely it will dribble that fuel into the intake tract.
An injector sprays at 58-62 PSI, immediately atomizing that at same rate every time, regardless of the air speed.

[WhipLash96]

It only makes sense because he probbaly has no clue as to how to program and tune FI bikes.     

I respect your opinion a lot but in this case I am laughing. (In a nice way). This engine builder's credentials are impeccable  and knows how to tune Fuel Injection.

[WhipLash96]

All things being optimally configured he is 100% wrong

Care to elaborate?

[Ohio HD]

It only makes sense because he probbaly has no clue as to how to program and tune FI bikes.     

I respect your opinion a lot but in this case I am laughing. (In a nice way). This engine builder's credentials are impeccable  and knows how to tune Fuel Injection.

Then why are you on here questioning his statement? You also said "It certainly defies logic for me".     

[kd]

As I stated before, my searches show more WFO power on the track.  I didn`t dig into how much but I expect not a huge difference and only on tap at the top when WFO.  The builder (if reputable and well known as said) may have been referring to what his dyno sheet will show but we all know what that means in real world full range performance.  He also said with the exact same set-up.  That may mean the OP is running cams more suited to carb intake.   

[JW113]

Think of it in terms of A/F ratio. If you have both carb and EFI dialed in for optimum A/F, then how does the motor know the difference? It don't! Both will make same power.

Also think of EFI as the latest pollution control device. There you have it...

-JW

[Ohio HD]

In general, FI offers a better atomization of fuel, meaning a better burn, more power. As well in general a motor can accommodate a larger bore TB than a carburetor, more flow means more power, as long as the motor can process the flow. This is of course speaking of gasoline powered motors.

[kd]

JW, Ohio,  I agree with that reasoning.  I do however remember threads on here discussing how some cams and their event timing etc. are better suited for EFI.  If it's "pulling" fuel from the beginning of the intake tract (longer intake duration??) instead of just air and injecting fuel vapor onto the back of the valve, One cam may work better than another.  That may be why the builder said "with the exact same set-up".  Maybe the present cams could hold it back on EFI? 

[HogMike]

I took my softail out today after reading this post just to see if I should change it to EFI.
It's a 2000 model, 95". Mild cam and heads to match.
It was so much fun riding the twisties and hitting the throttle on the uphill curves I decided to just quit messing with it and enjoy the ride.

[Hossamania]

I took my softail out today after reading this post just to see if I should change it to EFI.
It's a 2000 model, 95". Mild cam and heads to match.
It was so much fun riding the twisties and hitting the throttle on the uphill curves I decided to just quit messing with it and enjoy the ride.

I wouldn't even consider changing it, carbs are still fun!

[WhipLash96]

It only makes sense because he probbaly has no clue as to how to program and tune FI bikes.     

I respect your opinion a lot but in this case I am laughing. (In a nice way). This engine builder's credentials are impeccable  and knows how to tune Fuel Injection.

Then why are you on here questioning his statement? You also said "It certainly defies logic for me".     

I agree that his statement was very odd and came from nowhere. I can't explain it. That statement just hit me upside the head. 

[WhipLash96]

I took my softail out today after reading this post just to see if I should change it to EFI.
It's a 2000 model, 95". Mild cam and heads to match.
It was so much fun riding the twisties and hitting the throttle on the uphill curves I decided to just quit messing with it and enjoy the ride.

Here is the situation. I am running PIG RICH with this CV 51 and I am not able to get the afr into acceptable range. I have the stock CV 51 main in it  (248) and a 44 pilot in it and my rear cylinder is still at like 10.9 and the front cylinder is at 11.5. This is real time data as I have a set of Weggo's hooked up to the bike. My bike makes a lot of power for the cam choice at this current jetting but we all know that this isn't necessarily good to run at such a rich afr. I spoke to Bob Woods about this issue that I am not able to get this any better and he offered a solution for this, but, i can't justify the expense for a carb. Now I have a 58mm TB and all the other things needed to convert my bike to EFI as I have had it for a long time. What I want to do is to put the EFI on and retune. If I lose power as my builder suggests, i will put a different cam in. My fuel mileage SUCKS and understandably with that kind of AFR.

[WhipLash96]

I took my softail out today after reading this post just to see if I should change it to EFI.
It's a 2000 model, 95". Mild cam and heads to match.
It was so much fun riding the twisties and hitting the throttle on the uphill curves I decided to just quit messing with it and enjoy the ride.

I wouldn't even consider changing it, carbs are still fun!

They are when they working correctly.

[cheech]

Have you fooled with the needle in it?  See you mention pilot and main jet but not the needle. Seems in cruise range you'd be "on the needle".

[Don D]

The CV 51 is rich at low speeds. It needs emulsion tube changes and more air in the idle circuit.
Contact Gary Williams.  601-939-5861

[WhipLash96]

Have you fooled with the needle in it?  See you mention pilot and main jet but not the needle. Seems in cruise range you'd be "on the needle".

There has been talk about the needle in other conversations but nothing with the needle has been done at this point. That was the main reason why I called Bob Woods but he quickly told me that the needle isn't the issue.

[WhipLash96]

The CV 51 is rich at low speeds. It needs emulsion tube changes and more air in the idle circuit.
Contact Gary Williams.  601-939-5861

This is what I was suspecting and why I am considering the EFI with the bigger throttle body. It needs more air......

[Hossamania]

 Is your enrichener stuck open? Is the accelerator pump dribbling fuel? What other jetting have you tried? I can say the needle affected mine in power and mileage.

[rking1550]

I took my softail out today after reading this post just to see if I should change it to EFI.
It's a 2000 model, 95". Mild cam and heads to match.
It was so much fun riding the twisties and hitting the throttle on the uphill curves I decided to just quit messing with it and enjoy the ride.

Here is the situation. I am running PIG RICH with this CV 51 and I am not able to get the afr into acceptable range. I have the stock CV 51 main in it  (248) and a 44 pilot in it and my rear cylinder is still at like 10.9 and the front cylinder is at 11.5. This is real time data as I have a set of Weggo's hooked up to the bike. My bike makes a lot of power for the cam choice at this current jetting but we all know that this isn't necessarily good to run at such a rich afr. I spoke to Bob Woods about this issue that I am not able to get this any better and he offered a solution for this, but, i can't justify the expense for a carb. Now I have a 58mm TB and all the other things needed to convert my bike to EFI as I have had it for a long time. What I want to do is to put the EFI on and retune. If I lose power as my builder suggests, i will put a different cam in. My fuel mileage SUCKS and understandably with that kind of AFR.

Just curious. what was Bob Woods suggesting to fix the issue ? I'm in a similar situation with one of his  king 505 CV 51 carbs,  rich low rpms & not the best fuel mileage,   I average 32 mpg.

[WhipLash96]

I took my softail out today after reading this post just to see if I should change it to EFI.
It's a 2000 model, 95". Mild cam and heads to match.
It was so much fun riding the twisties and hitting the throttle on the uphill curves I decided to just quit messing with it and enjoy the ride.

Here is the situation. I am running PIG RICH with this CV 51 and I am not able to get the afr into acceptable range. I have the stock CV 51 main in it  (248) and a 44 pilot in it and my rear cylinder is still at like 10.9 and the front cylinder is at 11.5. This is real time data as I have a set of Weggo's hooked up to the bike. My bike makes a lot of power for the cam choice at this current jetting but we all know that this isn't necessarily good to run at such a rich afr. I spoke to Bob Woods about this issue that I am not able to get this any better and he offered a solution for this, but, i can't justify the expense for a carb. Now I have a 58mm TB and all the other things needed to convert my bike to EFI as I have had it for a long time. What I want to do is to put the EFI on and retune. If I lose power as my builder suggests, i will put a different cam in. My fuel mileage SUCKS and understandably with that kind of AFR.

Just curious. what was Bob Woods suggesting to fix the issue ? I'm in a similar situation with one of his  king 505 CV 51 carbs,  rich low rpms & not the best fuel mileage,   I average 32 mpg.

When I spoke to Bob, he was saying that the entire carb would have to be stripped down to the casting. There are three sealed passage ways that would need to be checked and repaired as needed. Cost= $700 minimum. Your gas mileage is same ball park as mine.

[WhipLash96]

Is your enrichener stuck open? Is the accelerator pump dribbling fuel? What other jetting have you tried? I can say the needle affected mine in power and mileage.

From just "feel" the choke is closed all the way. This "could be" a problem area as when I choke the bike to start it and once the bike is running, the bike does not idle up like it should. This leads me to think that what Bob Woods is saying is true, but do I really want to throw a grand at a carb?

[Hossamania]

Would a Mikuni 48 work? Easier install than EFI.
If you have all the parts for EFI, that may be the way to go. Plus the cost of tune.

[Hossamania]

What are the details of the motor?

[Hossamania]

Is your enrichener stuck open? Is the accelerator pump dribbling fuel? What other jetting have you tried? I can say the needle affected mine in power and mileage.

From just "feel" the choke is closed all the way. This "could be" a problem area as when I choke the bike to start it and once the bike is running, the bike does not idle up like it should. This leads me to think that what Bob Woods is saying is true, but do I really want to throw a grand at a carb?

I just reread your other thread about EFI conversion, add the cost of a new tank to your EFI conversion, where does that put the carb cost verses EFI install?

[rigidthumper]

It's been a minute, but the mods I remember doing were as follows- CV51 NDKS needle 48 Pilot, 210 main, #50 hole drilled into the plate, +4 Emulsion tube mod.  Drilling a #50 hole in the plate allowed me to set idle AFR with the idle mix screw. Before adding the hole, idle mix had no affect.
Adding the 4 holes in the emulsion tube (I followed the stock pattern, and size, just made new rows above the existing ones, deburring the inside when done) allowed me to have normal mid range, cruise upper 13s, and the main worked pretty well at WOT.

[capn]

Those afr meters dont work well at lower rpms with a big motor and long duration.I tried one and it told me I was rich.I rejetted leaner and bike ran like crap.Went back to what I had and got rid of the afr meter.120 cubes with S&S G.

[WhipLash96]

Would a Mikuni 48 work? Easier install than EFI.
If you have all the parts for EFI, that may be the way to go. Plus the cost of tune.

I could go to a Mikuni but a smaller carb on a 124? Going backwards in my opinion. Yes, it will cost me more to do the efi but the benefits of EFI vs Carb are worth it to me. As of now, all I need for the EFI is the fuel pump and some hoses. I have the tuner, ECM TB and so on.....

[WhipLash96]

Those afr meters dont work well at lower rpms with a big motor and long duration.I tried one and it told me I was rich.I rejetted leaner and bike ran like crap.Went back to what I had and got rid of the afr meter.120 cubes with S&S G.

Right. I have been taking readings from all over the RPM range and it has been pretty consistent. 

[kd]

If your AFR readings are less than optimal I would expect a conversion to a well tuned EFI to be better.  If you have a sheet and stats on your carb set-up, page through the dyno section for some 124 examples close to what you'll have.  They probably will be better than what you are describing.

[Admiral Akbar]

Would a Mikuni 48 work? Easier install than EFI.
If you have all the parts for EFI, that may be the way to go. Plus the cost of tune.

I could go to a Mikuni but a smaller carb on a 124? Going backwards in my opinion. Yes, it will cost me more to do the efi but the benefits of EFI vs Carb are worth it to me. As of now, all I need for the EFI is the fuel pump and some hoses. I have the tuner, ECM TB and so on.....

48 flows more than a 51.

[HogMike]

Would a Mikuni 48 work? Easier install than EFI.
If you have all the parts for EFI, that may be the way to go. Plus the cost of tune.

I could go to a Mikuni but a smaller carb on a 124? Going backwards in my opinion. Yes, it will cost me more to do the efi but the benefits of EFI vs Carb are worth it to me. As of now, all I need for the EFI is the fuel pump and some hoses. I have the tuner, ECM TB and so on.....

Sounds like you already made a decision.
Keep us posted how it all turns out.

[JW113]

I would suggest you exhaust all possibility to tune the CV51 before making any big decisions about changing it. I have one on my bike, it runs awesome, gets 45mpg or better (if I can keep the speed reasonable, that is!). The changes that rigidthumper described above is very similar to what I have in mine. Am I reading that right, you ave a 248 main jet? That seems WAY to big, I've got a 200 in mine, A/F is like 12.6 at WOT. If you have a cam with a lot of duration, which I'm guessing you do, these big motors will not hardly idle without opening up the throttle plate. When you do this, it exposes the first of the transfer ports and pulls fuel from there instead of from the idle jet port. This is why they run like crap and very rich at idle. Drilling an air bleed hole in the throttle plate is a must do on a big hot rod engine. You should really try that right away. And yes, needles make a big difference at the low/mid. I have an NDKT in mine, the leanest one from the HD tuner kit. And more holes in the emulsion tube is very helpful.

-JW

[WhipLash96]

Would a Mikuni 48 work? Easier install than EFI.
If you have all the parts for EFI, that may be the way to go. Plus the cost of tune.

I could go to a Mikuni but a smaller carb on a 124? Going backwards in my opinion. Yes, it will cost me more to do the efi but the benefits of EFI vs Carb are worth it to me. As of now, all I need for the EFI is the fuel pump and some hoses. I have the tuner, ECM TB and so on.....

Sounds like you already made a decision.
Keep us posted how it all turns out.

I just made up my mind yesterday what it is that I am going to do. I am going to go ahead and convert it to fuel injection.

[klammer76]

I gained 8 HP and 5 ft#'s of torque when I converted my 2002 FLH to Delphi efi.

[xlfan]

It's been a minute, but the mods I remember doing were as follows- CV51 NDKS needle 48 Pilot, 210 main, #50 hole drilled into the plate, +4 Emulsion tube mod.  Drilling a #50 hole in the plate allowed me to set idle AFR with the idle mix screw. Before adding the hole, idle mix had no affect.
Adding the 4 holes in the emulsion tube (I followed the stock pattern, and size, just made new rows above the existing ones, deburring the inside when done) allowed me to have normal mid range, cruise upper 13s, and the main worked pretty well at WOT.

Is the location of the #50 hole in plate critical?

[rigidthumper]

I placed it 1/2" down from the top, centered.

[rking1550]

I gained 8 HP and 5 ft#'s of torque when I converted my 2002 FLH to Delphi efi.

Do you know how much it cost to do the conversion, including tuner and tune ?

[WhipLash96]

I gained 8 HP and 5 ft#'s of torque when I converted my 2002 FLH to Delphi efi.

Good to hear! This is about what I would expect from this kind of change...