Join Today
Thanks Thanks:  1
Likes Likes:  1
Dislikes Dislikes:  0
Results 1 to 10 of 10
  1. #1
    Junior Member
    Join Date
    Jan 2017
    Location
    Harrisonburg, VA
    Posts
    19

    Smile Side Benefit of K & N RC-2400 Air Filter

    One of the unexpected benefits of my installation on the K & N RC-2400 air filter was the minimization (if not complete elimination of) the less than stellar performance in 6th gear from 38 - 45 mph. As all of us are aware (myself especially since I have a hack (sidecar) the CTX700 DTC in D shifts into 6th at 38 mph (unless under hard acceleration) and the stumble bumping (for want of a better term) is disheartening. That has been eliminated with the change in air filter. As noted in “What did you do to your CTX today” I removed the original air box and installed a new K & N RC-2400 air filter assembly, modified to accept the air temperature sensor and breather line.

    It may have been related to the near zero temp, but since the CTX is my daily driver, I often experience low temps and the performance around 38-45 (in 6th gear) has always been poor. Not so anymore. Might be worth considering as the mod is relatively cheap. Another benefit that I just realized after fueling up is a slight increase in mileage, ~5% increase noticed initially, then after the second tank, back to normal.

    Fred
    Last edited by dyenfd; 02-02-2018 at 08:59 AM.

  2. #2
    Senior Member MJC's Avatar
    Join Date
    May 2016
    Location
    Mid Hudson Valley, 60 miles N of NYC
    Posts
    382
    ? What you did was take the air temp sensor out of the air box and put it into the back of a open filter. So could you just remove it from the air box and just leave it in the open air? The air going around the K and N filter is going to be moving cold air all the time over the air sensor, so (guessing) the air temp sensor will never give a reading like being in the stock air box. Would doing this make the ecu (or whatever it is called) pump more gas into the mix? Cold air needs more fuel to make the engine run, so my guess is, yes the bike will run better in 6th gear at 38 mph because you now have more gas being used. How is this going to affect your MPG and is that good or bad for the engine. Can the ecu add that much gas to = out the new amount of air and the air temperature sensor not reading the right air temp?

    Just asking. This maybe a way to get more out of the cxt, but is it safe? I am not looking to start something, or being a smart ass. I talked to Honda and was told that the CTX DCT can not be made to get better performance out of it by opening up the air in-take (like we did on other bikes) and adjusting the ecu by adding a fuel controller (like we did on other bikes). This is what I was told because of the DCT.

    So keep us (me) posted on how it goes. thanks for the info and trying this air filter mod.

  3. Likes DaddyDave liked this post
  4. #3
    Junior Member
    Join Date
    Jan 2017
    Location
    Harrisonburg, VA
    Posts
    19
    Can't imagine that the air sensor would see a different air temperature in the air box than it would in the bottom of the RC filter. It is designed to measure the temperature of the air going into the engine, that will be close to ambient.

  5. #4
    Senior Member MJC's Avatar
    Join Date
    May 2016
    Location
    Mid Hudson Valley, 60 miles N of NYC
    Posts
    382
    dyenfd, Try this: In a room in your home, place a fan (blowing in) in the window, open the door to that room, turn fan on, take temps at the fan, the center of room and behind the open door. You will see that the air behind the door is warmer, the air at the center is cooler then behind the door, but the air temp at the fan is the coolest. By moving the temp sensor from the air box (like behind the door) and putting it at the open air filter (fan blowing in) you will get a lower temp reading. Moving air is always cooler. So in the factory air box the temp sensor was placed in a area where the incoming air was moving the least.

    By doing this (the factory) can save gas in the mix to the engine. What you did was come up with a way to add more fuel to the mix. I am not saying you are wrong or right for doing this, just that it is a cheap way to get more out of the engine. I do not think in doing this you where even trying to do this. But you did...

    I have a call into Honda, to ask if this change would be ok. I asked if the ecu could adjust the fuel mix (enough) so that the bike does not run lean. I will post when I get a reply.

    enjoy your day,
    mj

  6. #5
    Senior Member randy1149's Avatar
    Join Date
    Jun 2015
    Location
    Yonkers, 15 miles north of NYC.
    Posts
    541
    If I remember right if you move the air sensor outside the box won't the oxy sensors (in the exhaust) see the results of the extra fuel and tell the ECU to thin it out.
    I'm thinking the air sensor is the electronic replacement -the old choke on carbs.

  7. #6
    Senior Member MJC's Avatar
    Join Date
    May 2016
    Location
    Mid Hudson Valley, 60 miles N of NYC
    Posts
    382
    Rand1149, Yes you remember right! My thing is, can the ecu put more gas into the mix (after reading the air sensor) in the 1st place. If it can not then the bike will run lean.

    If the ECU can add more fuel (I know it can) will it add just the right amount or does it add too little.

    I know the oxy sensors (in the exhaust) can send info to the ECU a long with all the senors, this was my question. How or can the ecu handle the air sensor reading if it will always read cooler?

    When I 1st got my ctx700, I wanted to change the air intake and open up the exhaust, but could not find a unit to control (or change) the ecu. I had done this to many of my past bikes that where FI, and they run cooler and by my seat of pants meter, better. At that time, Honda told me, it could not be done, that the ecu could not handle that kind of changes, and there where no FI controls (aftermarket) to get. Honda made sure it could not be done by the way they made the exhaust, where the oxy/air temp etc sensors where placed.

    I am hoping dyenfd, found a way around this. If the ecu can keep up with what he did, that would be great! Just my view, I like Side Benefit of K & N RC-2400 Air Filter!

    Lets just wait for the Honda rep to get back to me and see if it is safe to do, we (I) do not want to make any changes that would make the CTX700 run lean.

    mj

    BTW, dyenfd ( I hope I got the right person) is working on a bigger fuel tank, great! I just wished I lived closer and could help. I got a welder...lol.

  8. #7
    Senior Member randy1149's Avatar
    Join Date
    Jun 2015
    Location
    Yonkers, 15 miles north of NYC.
    Posts
    541
    Quote Originally Posted by MJC View Post
    I know the oxy sensors (in the exhaust) can send info to the ECU a long with all the senors, this was my question. How or can the ecu handle the air sensor reading if it will always read cooler?
    I think we're giving the air sensor more power than engineered. The air sensor along with the engine temp. sensor gives info to the ECU for engine start. At a cold start both air and engine sensors show a cold engine data to the ECU. As the engine warms up the engine sensor will have a large swing while the air a small swing. So how much control do they give the air sensor... I think not much and very little (if any) affect with the sensor out of the air box. At the end of the day the oxy sensors rule the fuel/air ratio. And this maybe all nonsense.
    Last edited by randy1149; 01-18-2018 at 07:21 PM.

  9. #8
    Senior Member MJC's Avatar
    Join Date
    May 2016
    Location
    Mid Hudson Valley, 60 miles N of NYC
    Posts
    382
    Randy, I can not help it, it is the Engineer in me (LOL) I just have to know for sure if the ecu can adjust.

    I should have went to school when they did the FI, ecu classes, by that time I just finished the CNC classes on MRI's and I just could not take it any longer, I had to get out. LOL

    I do remember thinking, someday I would need to know more about ECU's and how they work and how to test and read in detail what was going on and how to program changes. But I was happy with relays and basic control boards. But who knew I would live this long.........bring back carbs!!

    Have a good day, mj

  10. #9
    Senior Member ponydrvr's Avatar
    Join Date
    Jul 2013
    Location
    Louisville, KY, USA
    Posts
    140
    The member Gonzo (on the "other" forum) has done quite a bit of delving into the ECU in a technical way. He is in Austraulia and may be able to help answer the question with a modicum of factual information. Good Luck in your quest.

  11. Thanks MJC thanked for this post
  12. #10
    Senior Member MJC's Avatar
    Join Date
    May 2016
    Location
    Mid Hudson Valley, 60 miles N of NYC
    Posts
    382
    Thanks for the info ponydrvr. I know Gonzo I will send him a email.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •