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Think that was taken from this forum and put on there.

No 'think' about it actually, as it was me who got the idea from a thread here and put it on over there.
 

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Not bad. I wonder what the cover actually does though. I never like to remove parts if I don't fully understand their role.
 

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Not bad. I wonder what the cover actually does though. I never like to remove parts if I don't fully understand their role.
Guess that when managing the air/fuel ratio and system they decided on the size of the airflow intake funnel that would best suit the stock version. They sealed this off and added the access cover so it's easy to get to the airfilter, and probably also to make modding the bike quite easy.

I think they really designed the stock version to be really quite tame compared to what the engine can really do. It's set up to be very easy to ride, great fuel economy and choked up to be green emission friendly.

I also think they purposefully made it very userfriendly to un-choke it and get it performing how it can. They put the lambda bung on the exhaust manifold to make a change of exhaust system very easy, and simply removing two screws and taking off the airfilter access cover gets about 3 times the airflow into the airfilter.

It's commonly thought that Honda will soon have maps for the ProGraMmed-Fuel Injection at selected dealerships, where you can take your CBR and have a new fuel map put on for a few $.
 

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cover

Careful with removing the cover. I ride mine rain or shine, and know for a fact that rain can find a way in there. If you were to get water in there, it would be bad news.
 

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Guess that when managing the air/fuel ratio and system they decided on the size of the airflow intake funnel that would best suit the stock version. They sealed this off and added the access cover so it's easy to get to the airfilter, and probably also to make modding the bike quite easy.

I think they really designed the stock version to be really quite tame compared to what the engine can really do. It's set up to be very easy to ride, great fuel economy and choked up to be green emission friendly.

I also think they purposefully made it very userfriendly to un-choke it and get it performing how it can. They put the lambda bung on the exhaust manifold to make a change of exhaust system very easy, and simply removing two screws and taking off the airfilter access cover gets about 3 times the airflow into the airfilter.

It's commonly thought that Honda will soon have maps for the ProGraMmed-Fuel Injection at selected dealerships, where you can take your CBR and have a new fuel map put on for a few $.
That makes sense. I'd just want to be sure before I start messing with the air intake on any vehicle.
 

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Yeah, for sure.

I took mine off, than put it back on a few days later as it felt it was running lean.

Something about the ECU sensor being by the throttle body or something.
 

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I dont understand how it would make the bike run lean, you are only removing the cover or in my case holesawed two holes in it so the cover would hold the filter tighter in the box...

Its not chainging the air capacity into the intake manifold, it is simply letting the bottom half of the airbox get more air, the manifold or intake manifold pipe has not changed in size and is still sucking the maximum amount of air it can hold with the cover on, taking the cover off just lets the filter breath easier without having it restricted.

And as for water getting in there, there is a hole at the bottom of the air box on the opposite size of "the cover" to let it drain water and also suck in air.
 

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I dont understand how it would make the bike run lean, you are only removing the cover or in my case holesawed two holes in it so the cover would hold the filter tighter in the box...

Its not chainging the air capacity into the intake manifold, it is simply letting the bottom half of the airbox get more air, the manifold or intake manifold pipe has not changed in size and is still sucking the maximum amount of air it can hold with the cover on, taking the cover off just lets the filter breath easier without having it restricted.
Ummm, you're kind of contradicting yourself. If it's not getting more air into the intake manifold then it can't possibly "breath easier". If the air intake is "restricted" then it's not pulling in the maximum amount of air into the intake manifold.
 

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Others will know a lot more about these things than me, but from the feel of the bike it felt like it was running lean. Also not sure why the ECU wouldn't adjust the fuel/air ratio to compensate, if there was indeed more air going in, but was told that the sensor is by the throttle body so wouldn't pick up the change.

I don't know about any of that. All I know is that it felt like it was running lean, and felt better when I put it back on.
 

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Refer to picture, number 11 is the cover you can take off or cut a hole in, in australia the cover retails for around $15 aud... Number 12 is the intake manifold pipe and does not change size so therefore the same amount of air with the cover on or off will go through. And also i have circled where the extra hole in the air box

 

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Nice diagram, but I still don't understand whether it affects the amount of air being taken into the engine or not. Or what affect it has on anything except the sound, and why/why not.
 

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If there is an "effect" on the sound of the engine. It does mean the airflow has changed. Many times in cars simply changing the airfilter can make the car sound very different. If you are using a higher surface area of your filter(which could happen by removing the cover) you will have less restriction. The ammount of air into the system will not change very much. If it does thats great because it means restriction was very high, although PGM,FI will need to be adjusted(which is rumored honda will be doing). So if you think you can get more out of this setup- GO FOR IT.
 

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This mod will allow a little more air flow but because you have a paper filter its still somewhat restrictive, change the filter to a K&N and you will get much more air flow. Yes , when they come out of course.
 

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They're yet to release a filter, yet to see any of the aftermarket companies release one yet actually.

Some people say that the ecu won't pick up a change from the airfilter and it'll run lean, some say the stock ecu range will be too limited.

Think there's many 'experts' with lots of opinions and facts but as a new bike nothing is proven yet.
 

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They're yet to release a filter, yet to see any of the aftermarket companies release one yet actually.

Some people say that the ecu won't pick up a change from the airfilter and it'll run lean, some say the stock ecu range will be too limited.

Think there's many 'experts' with lots of opinions and facts but as a new bike nothing is proven yet.
Here are the facts though.

The ECU IS adaptive

Here are 2 reasons why:
1. Fuel quality can be different depending on what gas station you go to so the computer needs to be able to adapt to it.

2. Elevation, this bike was meant to be driven anywhere you want it to. Not just at one location. Well if you live in the Mountains of Colorodo the air is thinner, if you live on the beaches of California the air is much thicker. The thicker air will need more fuel to burn w/o going lean so the ECU adapts. Removing this piece is going to be even less of a difference then the thicker air at sea level lol. You "Might" run a little close to the limit of the ECU's range if you are at sea level. But it's pretty doubtful because the ECU already has a pretty decent range of adaptivity.
 

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i also forgot to say as mention above, yes fuel quality and octane rating will effect if running lean or not in australia the lowest octane rating is 91 then 95 then 98... Im running the 95 as in australia we have had alot of problems with 98 octane fuel in bikes running around on THE STREET.
 

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Nice diagram, but I still don't understand whether it affects the amount of air being taken into the engine or not. Or what affect it has on anything except the sound, and why/why not.
hmmm. yeah, the amount of air taken into the engine is determined by it's displacement, that'd be somewhere around 250cc if I recall...

what matters is the power that it takes to get that air into the cylinder and that's a complicated question (as in tuned headers, etc)..
 

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Here are the facts though.

The ECU IS adaptive

Here are 2 reasons why:
1. Fuel quality can be different depending on what gas station you go to so the computer needs to be able to adapt to it.

2. Elevation, this bike was meant to be driven anywhere you want it to. Not just at one location. Well if you live in the Mountains of Colorodo the air is thinner, if you live on the beaches of California the air is much thicker. The thicker air will need more fuel to burn w/o going lean so the ECU adapts. Removing this piece is going to be even less of a difference then the thicker air at sea level lol. You "Might" run a little close to the limit of the ECU's range if you are at sea level. But it's pretty doubtful because the ECU already has a pretty decent range of adaptivity.
I have the two brothers racing exhaust installed and the I live in Hawaii so I am at sea level....I understand it is adaptive but other threads have said if I change both pieces out "Stock Exhaust and Stock Air Filter" I will run TOO lean and hurt the bike....is this true?
 

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I don't believe anyone has tested the CBR250R to get all the data/info with regards to the ECU, airfilter and exhaust changes. So don't believe anything is actual 'fact'.
 
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