[695]

Exhaust pipe changes and fuel management

I have question about changing the stock pipes and the cause and effect on the EFI system.
I read that just changing pipes without making consideration for the fuel management system will cause the motor to running too lean resulting in higher motor temperatures.
I see people changing the pipes and I am about to install the RAW Design pipes.
Does anyone know the facts about this topic?

I did notice that CobraUSA recommends the FI2000R fuel management module, and of course living in California they can only sell the FI2000R-ARB which is not adjustable. CobraUSA :::: :::: Fi2000 :::: ::::

Thanks for any feedback

 

[Hydroboy35th]

In short, yes.., you will need some sort of fuel management!

 

[Clueless]

Don't know the facts, but every other motorcycle I have seen with pipes has had something done to the fuel system, due to leaning the engine with the better breathing

 

[[email protected]]

Yes , the bikes are lean from the factory, and when you install a new exhaust, your going to be even leaner. install a fuel management system of some sort.Bikes do run hotter if they are lean.

 

[695]

What about with the baffles in?

Yes , the bikes are lean from the factory, and when you install a new exhaust, your going to be even leaner. install a fuel management system of some sort.Bikes do run hotter if they are lean.

Thanks for the responses, does the baffles left in help with the back pressure enough to not require the fuel management addition?

 

[centex]

I have the V & H Cruzers on my bike and it required no re-mapping. I did remove the baffles and had a small issue but it was a little too loud so I put them back in.

 

[crf325]

exhaust pipe changes

Its tough to believe people on here. S&S Cycle took a Fury ran it on a dyno in stock form. Then took stock exhaust and gutted it. There findings where almost the same as far as jetting was concerned. Little change was found. So that being said. I gutted my exhaust and it runs fine. Very little back firing on decel only but that is due to the pair valve putting air into exhaust.

 

[cycho]

The S&S dyno run doesn't include the AFR plot so I don't know what to say about that, however their recommendation appears to be to use a fuel controller.

Even in stock form this bike will benefit from a properly tuned mapp

Personally, I wouldn't change the airflow on my bike without knowing exactly how it affects the AFR, as doing so could do serious damage to the engine.

 

[crf325]

exhaust pipe changes

So you just stated that the bike could benefit from a fuel controller. If it is running that close to the lean side then honda should know about it. And if you read it all it was only at low RPM, not at mid to upper.

 

[OJGP]

In short, yes.., you will need some sort of fuel management!

Let's see...air and fuel enter the engine through the intake and the mixture of air and fuel is determined by everything in the intake...the airbox assembly, filter media, etc. After the mix enters the engine and is burned it is expelled through the exhaust. All said, yes altering the exhaust significantly affects how the engine performs (for example try totally plugging up the exhaust) but altering the exhaust has little, if ANY effect on whether or not the mix is lean or rich. Whatever the mix already is (lean or rich) can be magnified by altering the exhaust (because a less restrictive exhaust lets the engine "pump" more efficiently and, for example, existing lean conditions are more noticeable) but the actual mix itself stays pretty much the same because everything "mix wise" happens before the exhaust. Most of the time, exhaust changes don't require jetting (carbs) or re-mapping (FI) but when one starts altering the air intake, jetting or re-mapping is almost always required. That's not to say that if you change exhausts AND still fatten her up a little that you won't have much better performance (and usually less mpg). You just won't be near as "green".

 

[Scratch]

OJGP-

I am not a gearhead, don't know much about engines, exhausts or even lawnmowers. I'm a computer guy and this is the first bike I'm actually tinkering with. I read everything I can find and tend to overthink just about everything I do. With all of that said.. your previous post made this "exhaust thing" crystal clear for me. Seriously. Thanks.

 

[Scratch]

Dang it, I lied.. it's not clear. One question still on topic. What causes the blue-ing of the pipes? Running hot I would imagine and (now I'm guessing) is a result of not rejetting or remapping. Is that true?

Or is blue-ing of the pipes inevitable? Or is it just a result of an exhaust without an internal ceramic-coating?

 

[jwf15001]

I just want my pipes to get here I've been told September now.

I'll deal with the fuel management after I get them put on and let you all know.

 

[cycho]

No offense to anybody, but there is some flawed logic and theory being disseminated here.

Lets simplify and assume that the intake can flow 75 air units, the engine can flow 100 air units, and the exhaust can flow 75 air units. The engine in this configuration will only ever see 75 air units, because that's the max that either the front end, or rear end of the air path can flow. So, if I add an exhaust that can flow 100 air units, the engine will still only see 75 air units, because the intake is still the choke point. If I leave the stock exhaust, and add an intake that flows 100 air units, the engine still only sees 75 air units, because the the exhaust is the choke point. Now if I add an exhaust and an intake that both flow 100 air units, the engine now sees 100 air units. In this example we assume absoltues. In reality, this model is imperfect because changes at either end affect airflow velocity, which also affect airflow volume. The problem with our engine is that a fuel injector only flows a fixed amount of fuel. So if you make a change to the front, or rear end of the air flow path that affect the total volume of air moving through the engine, YOU NEED TO CHANGE THE AMOUNT OF FUEL FLOWING THROUGH IT TOO!

Now before you get all excited and refer back to S&S's findings, I'm not saying emphatically that changing the exhaust and keeping the stock exhaust, or vice versa, will burn up your engine, I'm just saying that IF YOU MAKE CHANGES TO YOUR ENGINE YOU SHOULD KNOW THE EFFECTS! Otherwise, you do so at the risk of your engine.

If you still think I'm full of $%^@, do some research on carburetion theory.

Good luck with your bike!

 

[Señor Gar]

So if you make a change to the front, or rear end of the air flow path that affect the total volume of air moving through the engine, YOU NEED TO CHANGE THE AMOUNT OF FUEL FLOWING THROUGH IT TOO! ...do some research on carburetion theory.

I don't see any mention of the Manifold Absolute Pressure (MAP) sensor here. As I understand EFI theory increased air flow results in a change in the MAP and a proportionately greater ON time for the fuel injector; i.e it does "change the amount of fuel".

I would be researching EFI theory although carburetion theory is very helpful in understanding Electronic Fuel Injection since EFI is designed to mimic every good aspect of the technology that it replaces.

Unfortunately no amount of theory can replace the accurate measurement that Honda used to create the EFI map with the stock components. The best solution for a modified exhaust and/or intake is to take dynamic measurements (at all engine loads and speeds) of the oxygen content in the exhaust. You can mount your own air/fuel ratio gauge and install an oxygen sensor in your exhaust or pay for a dyno run. The gauge allows you to first see if you need to remap and you can recheck if changes are made over time. If a fuel controller is needed an adjustable one would allow you to make the corrections you specifically require.

Worst case scenario without analysis would eventually be burnt (leaking) exhaust valves and loss of power.

 

[OJGP]

No offense to anybody, but there is some flawed logic and theory being disseminated here.

Lets simplify and assume that the intake can flow 75 air units, the engine can flow 100 air units, and the exhaust can flow 75 air units. The engine in this configuration will only ever see 75 air units, because that's the max that either the front end, or rear end of the air path can flow. So, if I add an exhaust that can flow 100 air units, the engine will still only see 75 air units, because the intake is still the choke point. If I leave the stock exhaust, and add an intake that flows 100 air units, the engine still only sees 75 air units, because the the exhaust is the choke point. Now if I add an exhaust and an intake that both flow 100 air units, the engine now sees 100 air units. In this example we assume absoltues. In reality, this model is imperfect because changes at either end affect airflow velocity, which also affect airflow volume. The problem with our engine is that a fuel injector only flows a fixed amount of fuel. So if you make a change to the front, or rear end of the air flow path that affect the total volume of air moving through the engine, YOU NEED TO CHANGE THE AMOUNT OF FUEL FLOWING THROUGH IT TOO!

Now before you get all excited and refer back to S&S's findings, I'm not saying emphatically that changing the exhaust and keeping the stock exhaust, or vice versa, will burn up your engine, I'm just saying that IF YOU MAKE CHANGES TO YOUR ENGINE YOU SHOULD KNOW THE EFFECTS! Otherwise, you do so at the risk of your engine.

If you still think I'm full of $%^@, do some research on carburetion theory.

Good luck with your bike!

Quick!!! You better spread this info to all of the major OEMs specifically HD that offer "performance" slip-ons and exhaust systems and use as a sales tool "no rejetting or re-mapping required". Just teasin'! Now specifically to your point...we need both fuel and air - the "mix". The amount of air that gets mixed with the fuel is way more dependant on it's path (and the restrictions therein) to the cylinder head than the restrictions on its way out. And it goes without saying you should NEVER make an exhaust change without closely following up to see if all is still good regarding the mix. Likewise, you should NEVER just automatically fatten things up without, again, checking to see that all is good with the mix. I didn't respond (at least I didn't mean to) in absolutes because there are so many variables out there in types and styles of systems, variations in manufacturer specs, and so on. What I will claim as MY absolute is that in MY experience, simply installing better performing & better sounding mufflers or exhaust systems on motorcyles and doing NOTHING to the OEM intake has never caused a lean condition. Never.

 

[OJGP]

Dang it, I lied.. it's not clear. One question still on topic. What causes the blue-ing of the pipes? Running hot I would imagine and (now I'm guessing) is a result of not rejetting or remapping. Is that true?

Or is blue-ing of the pipes inevitable? Or is it just a result of an exhaust without an internal ceramic-coating?

You are correct in that bluing is a result of heat. And the leaner the mix the higher the heat and the bluer the pipes. Optimum (in my experirence with v-twins) is a golden bronze color for the first 1/3 (or so) of the head pipe but it's hard to get that perfect. You will almost always see some bluing right at the headpipe cylinder head joint anyway. This is why God makes heat shields! Todays bikes are crazy lean right out of the box. The upside is at least they are designed for the high heat and fuel mileage is usually quite good. The downside is high heat, bluing, cold driveability issues, etc. Getting the mix perfect takes a lot of "playing" with it because every machine is a little different. FI is so much better than carbueration (thought I'd never say that!) but still everything in the fuel exhaust arena is compromise.

 

[695]

Great feedback..
I started this post in anticipation of getting the RAW Design Fury "Reaper" Exhaust tip's. Latest update, they are going to chrome on Monday so another couple weeks out.
Has anyone ordered and installed these yet?
I'm curious if the chroming truly matches with the stock fury pipes and how they perform.

With regards to the Fuel Management system, I'm stuck with the California emissions fixed fuel management system (ARB) non adjustable. Now CobraUSA recommends the FI2000R for their pipes (ARB) for California models. With that said, I have reservations with another fixed setting. They want $200.00 bucks for the Fuel Management module that cannot be adjusted. I have to see what the effects are by adding the reaper exhaust tips.
I need an address out of state to get the adjustable one...

Thanks for the feedback

 

[cycho]

I don't see any mention of the Manifold Absolute Pressure (MAP) sensor here. As I understand EFI theory increased air flow results in a change in the MAP and a proportionately greater ON time for the fuel injector; i.e it does "change the amount of fuel".

I would be researching EFI theory although carburetion theory is very helpful in understanding Electronic Fuel Injection since EFI is designed to mimic every good aspect of the technology that it replaces.

Never heard that one before. I'd think you'd need a forced induction system to increase the preassure in the manifold to the point that the ecu would adjust it. In any case, the amount of adjustment the ecu can make for this sensor (which as you probably know is intended to compensate for changes in altitude) is not enough to compensate for intake/engine/exhaust changes, otherwise DynoJet et al would be out of business.

I realize that this bike is fuel injected, but like you said, the principals are the same, and there is a lot more out there on carburetion.

Quick!!! You better spread this info to all of the major OEMs specifically HD that offer "performance" slip-ons and exhaust systems and use as a sales tool "no rejetting or re-mapping required". Just teasin'! Now specifically to your point...we need both fuel and air - the "mix". The amount of air that gets mixed with the fuel is way more dependant on it's path (and the restrictions therein) to the cylinder head than the restrictions on its way out. And it goes without saying you should NEVER make an exhaust change without closely following up to see if all is still good regarding the mix. Likewise, you should NEVER just automatically fatten things up without, again, checking to see that all is good with the mix. I didn't respond (at least I didn't mean to) in absolutes because there are so many variables out there in types and styles of systems, variations in manufacturer specs, and so on. What I will claim as MY absolute is that in MY experience, simply installing better performing & better sounding mufflers or exhaust systems on motorcyles and doing NOTHING to the OEM intake has never caused a lean condition. Never.

Teasing aside, HD and all the other manufaturers offer an IMPLIED WARRANTY when they make these statements, because if the product doesn't do what they say, they are liable. When manufacturers make these claims, you can be fairly certain that they've done extensive testing to ensure their products aren't going to cause problems. Back to my original point, and no disrespect to S&S, but are they offering a warranty to everyone who mods their bike like S&S did? Don't think so. So in this case, and I think we agree here, if you make changes to your bike, you should know and understand their effects.

I still disagree with you on your air path theories. Modifying the engine, and or the exhaust, can change the amount of air flowing through the engine IF they are the restrictive part of the path. More air = leaner mix. Period.

I do agree that in most cases, changing the exhaust and leaving the stock intake will probably not dramatically affect anything mix wise. Stock airboxes are fairly restrictive. However, I still believe that, in the absense of a manufacturers implied warranty, you should know what you are doing to your bike.

With regards to the Fuel Management system, I'm stuck with the California emissions fixed fuel management system (ARB) non adjustable. Now CobraUSA recommends the FI2000R for their pipes (ARB) for California models. With that said, I have reservations with another fixed setting. They want $200.00 bucks for the Fuel Management module that cannot be adjusted. I have to see what the effects are by adding the reaper exhaust tips.
I need an address out of state to get the adjustable one...
Thanks for the feedback

Dude, I think someone at CARB just scared a vendor or somehting here. As far as I know, It's not illegal to sell non CARB compliant devices in our state, it's just illegal to use them on anything besides off road, closed course competition vehicles. As soon as the 49 state models are more widely available, I'm sure you'll be able to get one from one of the bigger vendors. That's my plan anyway. For my Fury race bike, of course

 

[Señor Gar]

Now you have.

Never heard that one before. I'd think you'd need a forced induction system to increase the pressure in the manifold to the point that the ecu would adjust it. In any case, the amount of adjustment the ecu can make for this sensor (which as you probably know is intended to compensate for changes in altitude) is not enough to compensate for intake/engine/exhaust changes...

Cycho, I respectfully disagree so I will back up my statements. Unfortunately carburetors do not use MAP sensors or MAF sensors which are the primary fuel control input in any EFI system. Time to brush up on EFI theory. We tend to think of "manifold pressure" as a vacuum which draws fuel. In fact it is a pressure lower than atmospheric in terms of absolute (zero pressure or a true vacuum). As you will read if you follow the above link it is the BAP (barometric absolute pressure sensor) that is "intended to compensate for changes in altitude".

Since this is Tony's thread a word of advice to Tony:
Fueling modification is an art and a science best left to professionals or valve grinders .