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Thread: 2021 500 EXC-F FMF Slip on? ECU questtion

  1. #21
    KTMTalk Member DXC500's Avatar
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Fastway end cap and pull the intake baffles on my 2020. 500ohm resistor in the air temp wire nets 10 degree lower than ambient temp to ecu. Fatter curve more timing. almost as badass as my 2 smoke.
    No check engine lamp and 130 miles on 2 gallons o gas.

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  3. #22
    KTMTalk Member JamesDean's Avatar
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Quote Originally Posted by DXC500 View Post
    Fastway end cap and pull the intake baffles on my 2020. 500ohm resistor in the air temp wire nets 10 degree lower than ambient temp to ecu. Fatter curve more timing. almost as badass as my 2 smoke.
    No check engine lamp and 130 miles on 2 gallons o gas.
    That WOULD HAVE BEEN a very risky strategy with inadequate fueling in the upper rpm range, BUT NOT FOR THE 2020-2021 MODELS, here is why-

    Look at the torque curves below, and ask yourself how much additional fuel is needed to avoid running lean from an ALREADY lean stock EFI fuel mapping?

    If torque increases by 15-30%, then it stands to reason........... adding the same percentage of fuel is needed to make an acceptable air/fuel mixture, and not run lean.

    ***2019 and older model years did NOT have the O2 sensor on the header pipe, so the EFI system does not recognize any changes, nor does it make fueling corrections, so the 2019 (and older EXC-F motors) will run excessively lean wherever air flow and power is increased substantially!


    ***The 2020 and newer 350/450/500 EXC-F and XCFW models have an O2 sensor in the header pipe, which sends feedback to the ECU, and signals a need for more fuel when mods to intake/exhaust increase air flow thru the motor and increase torque/power output.

    To summarize, the closed loop fuel system found on 2020/2021 models with an O2 sensor in the header pipe, has a degree of self-correction when modifications are made, targeting an emissions-compliant 14.5:1 air/fuel mixture making lower power output than ideal.

    (as it stands, the motor is still running an emissions type lean when dropping out of closed loop operation, getting ~60mpg)






    ==============
    This piston is from a KTM EXCF owner that was told his bike had the EURO map installed, but the motor did not, and ran lean for an extended period under heavy loads in sandy conditions.

    Last edited by JamesDean; 11-21-2020 at 10:54 PM.
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  4. #23
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Just installed the Fastway end cap. First time pulling apart a muffler. I was surprised by the hair. I thought the packing would be just fiberglass. is that horse hair??

    Off my phone sound decibel meter (not super accurate but just a quick comparison) at idle from about 5 feet away went from 69/70db to 72db. A quick blip of throttle went from 72db to 75db.

    I plan to do a side by side comparison with a true db meter, of my 500 with endcap and my riding partner's 500 with stock, oem cap. Just to see how much if any difference it is making sound wise.

    How difficult is it to remove the internal baffles on the 2021? I just changed the endcap so far. I need to double check mine is an O2 sensor setup (closed loop) before I derestrict it further. But if so, just curious how challenging it is to remove that internal baffling, right now you can see the tail end of it.

    Oh, and these models (in South Africa) the factory endcap is below... no spark arrestor on the endcap. Just a reducing pipe from the full size down to the smaller outlet. And ours do not have the screens at the end either.

    Attachment 41886Attachment 41887Attachment 41888

  5. #24
    KTMTalk Member park5098's Avatar
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Quote Originally Posted by webnetxpress View Post
    Just installed the Fastway end cap. First time pulling apart a muffler. I was surprised by the hair. I thought the packing would be just fiberglass. is that horse hair??

    Off my phone sound decibel meter (not super accurate but just a quick comparison) at idle from about 5 feet away went from 69/70db to 72db. A quick blip of throttle went from 72db to 75db.

    I plan to do a side by side comparison with a true db meter, of my 500 with endcap and my riding partner's 500 with stock, oem cap. Just to see how much if any difference it is making sound wise.

    How difficult is it to remove the internal baffles on the 2021? I just changed the endcap so far. I need to double check mine is an O2 sensor setup (closed loop) before I derestrict it further. But if so, just curious how challenging it is to remove that internal baffling, right now you can see the tail end of it.

    Oh, and these models (in South Africa) the factory endcap is below... no spark arrestor on the endcap. Just a reducing pipe from the full size down to the smaller outlet. And ours do not have the screens at the end either.

    Attachment 41886Attachment 41887Attachment 41888
    Attachments are a real hit and miss on this board. Sometimes smaller ones work better. If I were living in SA, I would get an Akrapovic Muffler. There is another member on this board or Thumper Racing that says his full Akrapovic System is giving him 115mph on a 500. I have the 50 state street legal Akrapovic, although its not what I actually ordered. I was able to modify it but it look a lot of time and energy. I had to add back a Fische Spark Arrestor but its very open and not very loud at all....about like stock.

    2021 500 Six Days in the house!
    2020 500 Six Days Suspension by KreftMoto, Seat by Renazco Racing, GET powered with larger ThrottleBody and BDSB endcap.
    2015 500 XCW Euro Map, Full Dean Burke Motorsports Ohlins Suspension with Huck Valves in the forks
    2013 350 XCFW Vortex & A Kit SP Suspension ....lucky son

  6. #25
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Thanks.
    Its weird here bike wise. I havent been able to find a straight answer on what the SA bikes are.... are they EU spec or some specialized spec for SA.
    The exhaust is restrictive but doesnt have the screen at the outlet like the usa ones. but it is reduced smaller on the outlet. I think with this endcap change it will just open it up a little. I suspect our bikes were already running much more powerful than the usa ones. still sounded like a weedwacker. Hoping this cap gives it a bit more bark. The akrapovic for us in powerparts had the same size outlet as the street one. The dealer and I looked thru all the options trying to find a race option setup for the 2021 exc but nothing that they could find yet. So i went this route. I do know all of our stuff here is EU4 and EU5 compliant, so sound is significantly reduced.

    Will ride it thursday morning and see how it feels. Good'ol A-S-S dyno!

    Riding buddy has the same 2021 500 exc as me, only a month newer so it will be a good sound/power comparison between our two bikes.

  7. #26
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Have you removed the internal double cone baffle? If so, how?

  8. #27
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    interesting. so our SA 2021 500s do not have O2 sensors on the pipe. They have the nipple but no sensor...

  9. #28
    KTMTalk Member park5098's Avatar
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Quote Originally Posted by webnetxpress View Post
    interesting. so our SA 2021 500s do not have O2 sensors on the pipe. They have the nipple but no sensor...
    Strange. My 2021 Six Days 500 has the sensor. I use it for monitoring my AFR via the Koso Mini 3. https://www.youtube.com/watch?v=YgcOJzXfPjM

    2021 500 Six Days in the house!
    2020 500 Six Days Suspension by KreftMoto, Seat by Renazco Racing, GET powered with larger ThrottleBody and BDSB endcap.
    2015 500 XCW Euro Map, Full Dean Burke Motorsports Ohlins Suspension with Huck Valves in the forks
    2013 350 XCFW Vortex & A Kit SP Suspension ....lucky son

  10. #29
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Another try at the picture...
    Click image for larger version. 

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  11. #30
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    Default Re: 2021 500 EXC-F FMF Slip on? ECU questtion

    Quote Originally Posted by park5098 View Post
    Strange. My 2021 Six Days 500 has the sensor. I use it for monitoring my AFR via the Koso Mini 3. https://www.youtube.com/watch?v=YgcOJzXfPjM
    Would guess it has to do with the DOT (usa) emissions. But just guessing. I would think mine would have one as well but it doesn't. So now not so sure how much uncorking of the muffler I should do before worrying about mapping/fueling.

    Do the USA models have map options/switches standard?

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