Honda Rebel 300, 500, & 1100 Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
172 Posts
Discussion Starter · #1 ·
I ordered a DNA High Performance Air Filter for my 1100. I have a theory that this may reduce the annoying engine braking. If not at least I may get a few more ponies and torque. I put one (K&N) on my Sportster and it helped with the ponies and torque although the Sportster K&N filter also came with a velocity stack. I am guessing the Honda already comes with a well designed intake. I would suppose it is the same one on the Afrika Twin engine. Anyway I thought it would be worth a try. If you look closely at the two filters it appears to me Honda purposely restricted the air intake with the Honda filter with a metal plate that restricts air flow. In the video the stock screws will not work with the filter so I am wondering what size the stock screws are and what to replace them with. I already checked the manual and parts fiche. It should be required that every screw and bolt should have the size in the manual and on the parts fiche. I guess I will have to tear it apart and then run to the hardware store?

The Power Commander 6 is a no go in my country since we have frequent emission testing.

 

·
Registered
Joined
·
1,131 Posts
Edited: reading viewer comments in Burch's video the stock screws will work...read the video comments to find out

the screw size is listed in the parts fiche also noting it is a tapping screw

you can now disregard the following workaround

the screw thread size/length is not the problem..it's the diameter of the head that will not go down into the DNA High Performance Air Filter hole...a bench grinder would solve that head size problem

so when you look up the screw size in the parts fiche and then make your way to the store bring one of the original screws with to compare head size...screws of the same thread size and length necessarily don't have the same head diameter

I'd like to hear your theory on an air filter effecting engine braking.

.
 
  • Like
Reactions: GatorJoe

·
Registered
Joined
·
172 Posts
Discussion Starter · #3 · (Edited)
Edited: reading viewer comments in Burch's video the stock screws will work...read the video comments to find out

the screw size is listed in the parts fiche also noting it is a tapping screw

you can now disregard the following workaround

the screw thread size/length is not the problem..it's the diameter of the head that will not go down into the DNA High Performance Air Filter hole...a bench grinder would solve that head size problem

so when you look up the screw size in the parts fiche and then make your way to the store bring one of the original screws with to compare head size...screws of the same thread size and length necessarily don't have the same head diameter

I'd like to hear your theory on an air filter effecting engine braking.

.
Me no have a bench grinder and that is a hack if you ask me, okay in a pinch though.

Agree on the head size.

Thank you for the note on using the original screws.

"The term "engine braking" refers to the braking effect that occurs in gasoline engines when the accelerator pedal is released. This causes fuel injection to cease and the throttle valve to close almost completely, greatly restricting forced airflow from, for example, a turbocharger. The restriction causes a strong manifold vacuum which the cylinders have to work against, sapping much of the potential energy out of the system over time and producing the majority of the engine-braking effect."

Only a theory on the air filter since the closed throttle value has the primary effect. Since the air filter is over 40% less restrictive, air flows easier into the engine. This could possibly reduce the vacuum between the throttle valve and the air filter reducing the engine braking. Or perhaps the vacuum between those two is insignificant.

 

·
Registered
Joined
·
1,131 Posts
Me no have a bench grinder and that is a hack if you ask me, okay in a pinch though.

Agree on the head size.

Thank you for the note on using the original screws.

"The term "engine braking" refers to the braking effect that occurs in gasoline engines when the accelerator pedal is released. This causes fuel injection to cease and the throttle valve to close almost completely, greatly restricting forced airflow from, for example, a turbocharger. The restriction causes a strong manifold vacuum which the cylinders have to work against, sapping much of the potential energy out of the system over time and producing the majority of the engine-braking effect."

Only a theory on the air filter since the closed throttle value has the primary effect. Since the air filter is over 40% less restrictive, air flows easier into the engine. This could possibly reduce the vacuum between the throttle valve and the air filter reducing the engine braking. Or perhaps the vacuum between those two is insignificant.

I don't consider a modification to a part a "hack"...as in a poorly done or fitted mod. I could mod those screws heads and you would never know anything was done to them.

I'm pretty sure your theory on the increased air flow of high performance air filters effecting engine braking is wrong.

The OEM filter will pass more air than the engine will ever need when changed at recommended intervals,

The amount of engine braking applied is determined by throttle plate position as you mentioned thus effecting the amount of manifold vacuum and engine drag. I don't think a high flow filter would make any appreciable difference in lowering the manifold vacuum. If you want less engine braking set up the user mode to your liking and the ECU will control the plate opening to a wider position.

Do you ever wonder how they achieve high air flows? Maybe a more porous media with the effect of letting more contaminants in?

Does DNA have dyno charts available showing any performance gains on a filter swap on a stock engine...preferably a CMX 1100?

Honda's airboxes/filters, ECU management controls and exhaust systems are tuned...messing with them without a re-tune usually doesn't accomplish any gains.
 
  • Like
Reactions: Kenny G

·
Registered
Joined
·
172 Posts
Discussion Starter · #5 ·
I don't consider a modification to a part a "hack"...as in a poorly done or fitted mod. I could mod those screws heads and you would never know anything was done to them.

I'm pretty sure your theory on the increased air flow of high performance air filters effecting engine braking is wrong.

The OEM filter will pass more air than the engine will ever need when changed at recommended intervals,

The amount of engine braking applied is determined by throttle plate position as you mentioned thus effecting the amount of manifold vacuum and engine drag. I don't think a high flow filter would make any appreciable difference in lowering the manifold vacuum. If you want less engine braking set up the user mode to your liking and the ECU will control the plate opening to a wider position.

Do you ever wonder how they achieve high air flows? Maybe a more porous media with the effect of letting more contaminants in?

Does DNA have dyno charts available showing any performance gains on a filter swap on a stock engine...preferably a CMX 1100?

Honda's airboxes/filters, ECU management controls and exhaust systems are tuned...messing with them without a re-tune usually doesn't accomplish any gains.
All the points you make are good ones.

I have the EB set as low as it will go and it is still annoying. I wish I could tweak that setting in the ECM. It should not react so harshly when rolling off the throttle versus cutting the throttle.

I would never use this filter on a dirt bike however

- HOW EFFICIENT ARE K&N® FILTERS AT TRAPPING CONTAMINANTS?
Laboratory tests utilizing ISO 5011 test protocols demonstrate that most K&N® air filters achieve overall filtration efficiency in the range of 97% to 99%. (The ability of an air filter to protect an engine is generally measured in accordance with laboratory testing procedure ISO 5011.) K&N® air filter designs are subjected to ISO 5011 testing involving coarse and fine test dust, and the test results are measured by a specific air filtration efficiency number. K&N® filters are designed to provide exceptional airflow while simultaneously targeting an overall filtration efficiency that meets or exceeds OEM standards.

- DOES INCREASED AIRFLOW MEAN THAT MORE DIRT WILL GET THROUGH THE FILTER?
No. Most disposable filters are "barrier filters" which act as a physical barrier to dust particles. Once a dust particle covers a pore in the media, air can no longer flow through that space. K&N® replacement air filters are designed to absorb dirt and dust particles instead of physically blocking them, allowing the pores in the material to continue flowing air.

I would say that most companies use paper air filters because of cost and profits selling new filters. No need to debate just an opinion.

There are dyno charts for K&N filters showing the HP difference. I have one for my Sportster on paper.

As for the ECM, the mass air flow sensor will detect the increased air flow and adjust the fuel accordingly.

I will report back here with my seat of the pants impressions. I know on the Sportster it made a difference however that was with a velocity stack so I am less hopeful for the Honda. I likely will not change the filter until the spring since the weather is now down to freezing and the garage is unheated.
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #6 ·
Another thing to consider. The Afrika Twin has two filters that are of equal size to the Rebel's single filter. One filter per cylinder so the Rebel is trying to pull double the air well not exactly since the camshaft and the piston phase timing also effects the airflow. Anyway, one filter with one intake tract to one cylinder on the Twin. On the Rebel two cylinders sharing one filter with one intake tract.

Since it is not sensible to install another air filter and intake tract on the Rebel it may make sense to let the engine breath a little easier with a hi-flow filter.

I'll let you all know when I find out.
 

·
Registered
Joined
·
395 Posts
EB is increased from the lack of fuel. Fuel is cut off below a certain throttle position so you have to open the throttle just until fuel begins flowing again to reduce the effective EB. Then, you get an on/off switch effect with most bikes which can only be cured with an ECU flash which will smooth out those twitchy throttle transitions and reduce maximum EB.
 

·
Registered
Joined
·
452 Posts
Me no have a bench grinder and that is a hack if you ask me, okay in a pinch though.

Agree on the head size.

Thank you for the note on using the original screws.

"The term "engine braking" refers to the braking effect that occurs in gasoline engines when the accelerator pedal is released. This causes fuel injection to cease and the throttle valve to close almost completely, greatly restricting forced airflow from, for example, a turbocharger. The restriction causes a strong manifold vacuum which the cylinders have to work against, sapping much of the potential energy out of the system over time and producing the majority of the engine-braking effect."

Only a theory on the air filter since the closed throttle value has the primary effect. Since the air filter is over 40% less restrictive, air flows easier into the engine. This could possibly reduce the vacuum between the throttle valve and the air filter reducing the engine braking. Or perhaps the vacuum between those two is insignificant.

What he sais reducinf the size of a screw head ie not a HACK
Me no have a bench grinder and that is a hack if you ask me, okay in a pinch though.

Agree on the head size.

Thank you for the note on using the original screws.

"The term "engine braking" refers to the braking effect that occurs in gasoline engines when the accelerator pedal is released. This causes fuel injection to cease and the throttle valve to close almost completely, greatly restricting forced airflow from, for example, a turbocharger. The restriction causes a strong manifold vacuum which the cylinders have to work against, sapping much of the potential energy out of the system over time and producing the majority of the engine-braking effect."

Only a theory on the air filter since the closed throttle value has the primary effect. Since the air filter is over 40% less restrictive, air flows easier into the engine. This could possibly reduce the vacuum between the throttle valve and the air filter reducing the engine braking. Or perhaps the vacuum between those two is insignificant.

What he said not a hack, it is a modification ....like replacing the air filter with an aftermarket, no grinder? how about a hand held drill motor and a file?
 

·
Registered
'21 Rebel 1100, '15 CTX 700
Joined
·
256 Posts
I don't understand how engine braking would be undesirable. As I approach a turn I downshift and the engine braking slows me for the turn, and the lower gear helps me accelerate out of it. If a stop is coming up I downshift to as needed and then apply brakes.
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #10 ·
I don't understand how engine braking would be undesirable. As I approach a turn I downshift and the engine braking slows me for the turn, and the lower gear helps me accelerate out of it. If a stop is coming up I downshift to as needed and then apply brakes.
Engine braking is not bad. It is the abrupt engine braking when rolling off the throttle. The throttle is very sensitive to triggering abrupt engine braking compared to throttle by cable versus throttle by wire. The computer does not seem to understand rolling off the throttle versus killing the throttle. If I quickly close the throttle then I want maximum engine braking now, if I slowly roll off the throttle then I want a gradual buildup of engine braking proportional to how fast I rolled off the throttle. It would not be hard to add a little code to the ECU to give it this behavior.

LifeofBurch even mentioned it in the video I posted.
 

·
Registered
2021 Honda CMX1100 DCT
Joined
·
165 Posts
Not sure I would want to increase the Air Flow without a Tuner .. Have not seen this mentioned often, but the with the new EPA laws a stock Motorcycle is quite lean these days and to add air would give you more power but without a tuner to add fuel as well I would be a bit worried ..
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #12 ·
Not sure I would want to increase the Air Flow without a Tuner .. Have not seen this mentioned often, but the with the new EPA laws a stock Motorcycle is quite lean these days and to add air would give you more power but without a tuner to add fuel as well I would be a bit worried ..
The ECM measures the air going into the engine via the mass air flow (MAF) sensor and adjust the fuel to air ratio according to the amount of air so the bike will not run lean. I suppose there is a point where the ECM cannot compensate and / or the MAF sensor cannot measure however this is very unlikely without a turbo on the engine.

Also no company is going to sell you an air filter that will destroy your engine without warning labels that the ECM needs to be tuned for the filter.

I did this to my Sportster without any problems. Now on a Sportster you should not replace the muffler with a non cat muffler without tuning the ECM since the change in exhaust back pressure could cause engine problems like burnt valves. I've notice many Rebel owners changing the mufflers without problems and I believe this is because the cat is not in the muffler on a Rebel where on a Sportster the cat is in the muffler.
 

·
Registered
Joined
·
395 Posts
The ECM measures the air going into the engine via the mass air flow (MAF) sensor and adjust the fuel to air ratio according to the amount of air so the bike will not run lean.
Bikes use a Manifold Absolute Pressure (MAP) sensor and can compensate quite a bit for the extra air and to a greater extent than a MAF sensor but they'll still run leaner than stock. Both do a way better job than a carburetor which can't compensate at all.

Because of the different ways they detect how much fuel would be needed, a MAP sensor will add more fuel if there's a manifold leak but a MAF sensor will subtract fuel.
 

·
Registered
Joined
·
172 Posts
Discussion Starter · #14 ·
Bikes use a Manifold Absolute Pressure (MAP) sensor and can compensate quite a bit for the extra air and to a greater extent than a MAF sensor but they'll still run leaner than stock. Both do a way better job than a carburetor which can't compensate at all.

Because of the different ways they detect how much fuel would be needed, a MAP sensor will add more fuel if there's a manifold leak but a MAF sensor will subtract fuel.
Thank you for the additional information.

The Rebel 1100 uses a MAP sensor according to the service manual. Not a MAF sensor as I wrote. It appears the MAP sensor will do a better job compensating for additional air than a MAF. My Sportster has a TMAP sensor according to the manual.

I pulled this out of the Wikipedia,

"The manifold absolute pressure sensor provides instantaneous manifold pressure information to the engine's electronic control unit (ECU). The data is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion (see stoichiometry) and influence the advance or retard of ignition timing."

 
1 - 14 of 14 Posts
Top