Bike running rich after mods

[bluestratos]

After I removed the cat and installed a performance air cleaner and muffler I had some minor popping in the exhaust so I installed a fuel controller. I turned it off so the bike could first try to relearn but I kept thinking.. I thought popping in the muffler was from a too rich condition but everyone said I would be too lean. Well I pulled the plugs and they were fine but on the rich side in color. Then I hooked up a fuel/air ratio meter and took it for a run.. yup, it runs pretty much right on except at full open throttle and when de-accelerating it is clearly running too rich. I turned on my fuel controller but noticed it was no longer making a dramatic change when switched to one. Sure enough, it was exactly the same, rich on wide open and on de accel.

The readings are hard to really explain but they drop into the low 14's and down into the 13's. The indicator light turn red when averaging too rich and it was full and steady. I will play with the controller a bit more but I may just have to get a more intelligent one. Ok... so... why not lean as would be expected? The rich issue explains why my fuel mileage is lower than most, I average 27.

[NancysToy]

If I had to guess, I'd say the free flow in your modified exhaust system is causing the OEM O2 sensors to read falsely lean, so the ECM is richening things up. Another possibility would be that the exhaust got too "free" so it got lazy and no longer scavenges the gasses as it did (low velocity). Everything you do when modifying an engine and intake/exhaust is a balancing act. you can go too far, especially if you do not have a means to tune the fuel system or valve timing to take advantage of your mods. You are in uncharted territory here. I wish you well in solving the riddle.

[DrewNJ]

If you dont mind, Post up which fuel controller, Map, Mods your running.
Wide open throttle the stock ECM goes to open loop (no o2 input). I see pretty consistent 12.5 on WOT.
Figure mid 13's is what id call "ideal" for most situations, also to be a bit richer for heavier throttle loads and a bit leaner for lighter loads is what your looking for too. We have a much larger safe area not having forced induction so as long as your not seeing 16+ or below 11 your in the ballpark.

Most people assume popping is due to being lean, which it can be. However, your correct, it can be due to rich unburnt fuel igniting on decel as well as an exhaust gasket leak. Many machines decel pop no matter what you do but it's not heard with a quiet exhaust.
I think many people dump fuel on decel to stop the popping. Basically, so much fuel that it won't ignite....lol.

Kudos for approaching tuning the correct way with a meter, so you can actually see what's going on and adjust accordingly.


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[bluestratos]

Right now I have a Dyna Boost by magnum tuning. I just ordered the Power Commander V so I will install that and try some of the maps other have used. The spark plugs tell me it has been running rich all along since I kept the plugs that I took out before I took out the cat, changed the muffler and installed the air cleaner. Mind you, the plugs are brown, not black so it is only slightly on the rich side from what I recall.

[NancysToy]

If you dont mind, Post up which fuel controller, Map, Mods your running.
Wide open throttle the stock ECM goes to open loop (no o2 input). I see pretty consistent 12.5 on WOT.
Figure mid 13's is what id call "ideal" for most situations, also to be a bit richer for heavier throttle loads and a bit leaner for lighter loads is what your looking for too. We have a much larger safe area not having forced induction so as long as your not seeing 16+ or below 11 your in the ballpark.

Most people assume popping is due to being lean, which it can be. However, your correct, it can be due to rich unburnt fuel igniting on decel as well as an exhaust gasket leak. Many machines decel pop no matter what you do but it's not heard with a quiet exhaust.
I think many people dump fuel on decel to stop the popping. Basically, so much fuel that it won't ignite....lol.

Kudos for approaching tuning the correct way with a meter, so you can actually see what's going on and adjust accordingly.


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Good points, and all true. Most people would be very satisfied with a street machine that ran tan to brown plugs with an A/F ratio in the mid 13's under normal operations. The loss in gas mileage could be attributed to the free flowing exhaust and intake...more air requires more fuel.

[Magdave]

If you are talking A/F ratios 14 is lean not rich it is near the lean side. 13 and below is rich side. I believe average is ~13.5 that is what the factory is tuned to. Better rich than lean. Lean engines go.....boom.

[DrewNJ]

Actually, during closed loop the o2 sensor tries to push it to 14.7. However, a narrowband o2 sensor is like an on/off switch so you'll see a lot of fluctuation when using the o2. Your numbers will constantly go above then below, back and forth.
This is also why that unless your fuel controller also modifies the o2 signal, you have very limited control and it will be a bastard to get a consistent tune. The signal from the o2 will cause the ECM to compensate for many (not all) attempts to richen things up.

Again, these are NA motors so they are much more comfortable at slightly higher AFR numbers. Forced induction and those mid 13 numbers can be the boom motors....lol.




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[DrewNJ]

Also, I honestly think many people over react adding fuel controllers. People hear popping exhaust and slap a fuel controller on there.
The stock system does a pretty decent job adjusting on its own. We have one 2011 RS running only a pipe and the AFR numbers are dead on, even in the 30 degree cold air.


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[NancysToy]

Also, I honestly think many people over react adding fuel controllers. People hear popping exhaust and slap a fuel controller on there.
The stock system does a pretty decent job adjusting on its own. We have one 2011 RS running only a pipe and the AFR numbers are dead on, even in the 30 degree cold air.


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:agree: Many people don't realize that a side effect from a large diameter, free-flowing exhaust can be the easier introduction of fresh air into the exhaust discharge when the throttle is closed, resulting in ignition of any fuel that is in the muffler, often as a result of the same sudden deceleration.

[Bob Denman]

This is why I'd much rather leave an EFI engine alone... :shocked: nojoke
At least you can unbolt a carburetor, and beat it against something... :D

[cuznjohn]

i really don't understand all of what you are talking about, if a bike runs rich or lean does it have a effect on the heat the bike puts out. i am not trying to hijack the tread but i am really interested in this. when i bought the bike i had the aprvoake exhaust put on the bike b4 i ever took the bike for the first ride. now friends of mine look at my exhaust and tell me the bike is running rich, could that cause heat problems. i have the stock exhaust and i wanted to put it back on to see if there is a difference in the way the bike runs. i also looked at the power commander with auto tune because of all the adjustments i would have to do w/o the auto tune, do you think that would help. what do you smart people think.

[Bob Denman]

John, Ust pull the Akrapovic off, and slide the OEM back under it...
:lecturef_smilie:ONE change at a time!
That way you know what causes the changes... it's easier to un-do them also! :thumbup:

[CyncySpyder]

After I removed the cat and installed a performance air cleaner and muffler I had some minor popping in the exhaust so I installed a fuel controller. I turned it off so the bike could first try to relearn but I kept thinking.. I thought popping in the muffler was from a too rich condition but everyone said I would be too lean. Well I pulled the plugs and they were fine but on the rich side in color. Then I hooked up a fuel/air ratio meter and took it for a run.. yup, it runs pretty much right on except at full open throttle and when de-accelerating it is clearly running too rich. I turned on my fuel controller but noticed it was no longer making a dramatic change when switched to one. Sure enough, it was exactly the same, rich on wide open and on de accel.

The readings are hard to really explain but they drop into the low 14's and down into the 13's. The indicator light turn red when averaging too rich and it was full and steady. I will play with the controller a bit more but I may just have to get a more intelligent one. Ok... so... why not lean as would be expected? The rich issue explains why my fuel mileage is lower than most, I average 27.


If I had to guess, I'd say the free flow in your modified exhaust system is causing the OEM O2 sensors to read falsely lean, so the ECM is richening things up. Another possibility would be that the exhaust got too "free" so it got lazy and no longer scavenges the gasses as it did (low velocity). Everything you do when modifying an engine and intake/exhaust is a balancing act. you can go too far, especially if you do not have a means to tune the fuel system or valve timing to take advantage of your mods. You are in uncharted territory here. I wish you well in solving the riddle.


I too have had the same/similar issue that you describe (popping on de-acceleration/ Lower MPGs) for almost a year now, ever since we removed the OEM airbox/resonator & replaced it with the KewlMetal Air Intake as you did.

Unlike you however, we have made no other changes to our OEM system, at least when it comes to running the stock Pipes, Cat & even the stock muffler. The only other change that we made that might also have some barring on our situation (but I doubt it) was that we also changed out the OEM Plugs & Wires for the better offerings from BajaRon at the same time as we did the AirBox mod.

So it would seem, from our similar experiences, that the modified exhaust system would have little to no effect on the situation...... no? I'm just thinking logically here & could be way off base, but if we both did the intake mod with the same/similar results, and one modified the exhaust system and the other didn't, and we both still have similar if not the same results, it would seem to take the modified exhaust system out of the equation......... right?

I think most of you know that I'm far from any type of expert, and like many, am learning as I go here & I understand that the exhaust usually DOES play a large roll in what we're discussing here, but it seems we do have similar results and are both searching for the right combination of software/hardware to make everything work at its most optimal. Thoughts??? Theory's??? Discussion???

[Magdave]

i really don't understand all of what you are talking about, if a bike runs rich or lean does it have a effect on the heat the bike puts out. i am not trying to hijack the tread but i am really interested in this. when i bought the bike i had the aprvoake exhaust put on the bike b4 i ever took the bike for the first ride. now friends of mine look at my exhaust and tell me the bike is running rich, could that cause heat problems. i have the stock exhaust and i wanted to put it back on to see if there is a difference in the way the bike runs. i also looked at the power commander with auto tune because of all the adjustments i would have to do w/o the auto tune, do you think that would help. what do you smart people think.

I think that is a question for another thread :thumbup:

[DrewNJ]

i really don't understand all of what you are talking about, if a bike runs rich or lean does it have a effect on the heat the bike puts out. i am not trying to hijack the tread but i am really interested in this. when i bought the bike i had the aprvoake exhaust put on the bike b4 i ever took the bike for the first ride. now friends of mine look at my exhaust and tell me the bike is running rich, could that cause heat problems. i have the stock exhaust and i wanted to put it back on to see if there is a difference in the way the bike runs. i also looked at the power commander with auto tune because of all the adjustments i would have to do w/o the auto tune, do you think that would help. what do you smart people think.

When it comes to tuning. Lean motors run hotter than rich motors.
My pops used to say back in the day..."Lean is mean, Fuel is cool".
Changing only the exhaust should have no significant effect on an EFI motor in relation to running lean enough to worry about heat......assuming everything was good before the exhaust change...


I too have had the same/similar issue that you describe (popping on de-acceleration/ Lower MPGs) for almost a year now, ever since we removed the OEM airbox/resonator & replaced it with the KewlMetal Air Intake as you did.

Unlike you however, we have made no other changes to our OEM system, at least when it comes to running the stock Pipes, Cat & even the stock muffler. The only other change that we made that might also have some barring on our situation (but I doubt it) was that we also changed out the OEM Plugs & Wires for the better offerings from BajaRon at the same time as we did the AirBox mod.

So it would seem, from our similar experiences, that the modified exhaust system would have little to no effect on the situation...... no? I'm just thinking logically here & could be way off base, but if we both did the intake mod with the same/similar results, and one modified the exhaust system and the other didn't, and we both still have similar if not the same results, it would seem to take the modified exhaust system out of the equation......... right?

I think most of you know that I'm far from any type of expert, and like many, am learning as I go here & I understand that the exhaust usually DOES play a large roll in what we're discussing here, but it seems we do have similar results and are both searching for the right combination of software/hardware to make everything work at its most optimal. Thoughts??? Theory's??? Discussion???

Dave, I know your not going to want to hear this....but as clean a setup as that kewlmetal intake is, I would expect it to cost you a few MPG's due to the design. Longer intake tracts and tubes typically increase torque. Shorter intake tracts have the ability to somewhat increase HP but will sacrifice some of that low end torque.
Personally, I think if your happy with the intake, don't worry about the MPG's.

[bluestratos]

I read more about closed loop systems and the results I am seeing on my Air Fuel Ratio meter matches the program curves as explained. I am running perfectly in wide range and exactly as would be expected in the idle and wide open throttle. That also seems to make sense why my fuel controller seems to make more change at idle than any where else since we are open loop at idle. The fuel controller can make the bike run leaner or richer at idle since there is no feed back adjustments going on. Once I am off idle the computer compensates for most of any adjustments I make and negates its affect.

A couple things need to be remembered. First, the popping was likely always there based on the fact that the system also goes open loop at wide open throttle, its just easier to hear now that the cat is gone which acted as a resonator.

The bike is running slightly rich based on the plugs but not overly so as to raise any alarms. Again, the ECM is compensating for the changes nicely under normal operating conditions.

What about O2 eliminators.. you using them?

[DrewNJ]

This is why I'd much rather leave an EFI engine alone... :shocked: nojoke
At least you can unbolt a carburetor, and beat it against something... :D

I used to feel the same way Bob. I was a hardcore carb guy since I was a little tot. It was my kid getting into supercharged jetskis that made me see the light.
It's SO much nicer to bench tune a motor with a laptop vs. having to pull, disassemble and rejet carbs! ;)

The key is to do it right and have the proper tools to be able to see what your changes are directly doing to the motor. This is where simple AFR meters or better yet, data logging equipment is so benificial..
It still amazes me that many people tune blind or with their butt dyno...twisting pots and pushing buttons...:yikes:

[DrewNJ]

I read more about closed loop systems and the results I am seeing on my Air Fuel Ratio meter matches the program curves as explained. I am running perfectly in wide range and exactly as wood be expected in the idle and wide open throttle. That also seems to make sense why my fuel controller seems to make more change at idle than any where else since we are open loop at idle. The fuel controller can make the bike run leaner or richer at idle since there is no feed back adjustments going on. Once I am off idle the computer compensates for most of any adjustments I make and negates its affect.

A couple things need to be remembered. First, the popping was likely always there based on the fact that the system also goes open loop at wide open throttle, its just easier to hear now that the cat is gone which acted as a resonator.

The bike is running slightly rich based on the plugs but not overly so as to raise any alarms. Again, the ECM is compensating for the changes nicely under normal operating conditions.

What about O2 eliminators.. you using them?

Great info!
Yes, I'm running an o2 eliminator. IMHO o2 sensors are in place for only one primary reason. Emissions. One side effect is that they do help with mileage too.

[Bob Denman]

:agree: But that entire, "Old dog and new tricks" thing can be tough to overcome... :shocked:
I used to LOVE jetting and clutching challenges when I was snowmobiling... :2thumbs: I spent an entire season dialing in a 1992 Polaris XCR 440 that had everything but the paint changed...
Bored, stroked, piped, ported, carbs bored, gearing AND clutching changes...
We even did a backyard upgrade to the coolant system added a radiator to it!
Those "39.5mm "Mikes" took a lot of time and patience to get just right...
When it was done; it was magic to pull the trigger on it! nojoke
The only sled that ever bested it was a D&D "660ed" ZR440; he jumped me with better traction, but would have had me anyway... :sour: