Live mapping SPS and TPS - 2008 CRF450R
  • mframpton
    Posts: 17
    Joined: Sat Nov 25, 2017 10:39 am

    Live mapping SPS and TPS - 2008 CRF450R

    by mframpton » Thu Apr 18, 2019 9:05 am

    I was shocked while tearing down my 08 450R and removed the throttle position sensor from the carb and only to read minutes afterward from the manual 'don't take this off'. Ha, figures. Anywise, I got it set back in range according to the shop manual formula and buttoned it up. For its function I learned here that the resistance changes with throttle position to adjust spark timing. I could only assume this is analog 1/rc tank circuit timing.

    Then I got my lesson in shift position sensor from this forum. I learned that 1st and 2nd gear run with respective timing retard to make it more manageable. Which kind of explains a lot. I love doing slow, 12 oclock wheelies but my 08 always feels heavy and takes a huge clutch dump to get it vertical.

    I'd have to look through the schematics but I'm thinking both of the above are the same 1/rc circuitry. It wouldn't take a lot of effort to extend fine adjustment to a switch system on the bars or maybe even a temporary potentiometer for discovery purposes.
  • Back2-2
    Posts: 1148
    Joined: Tue Jan 04, 2011 3:31 pm

    Re: Live mapping SPS and TPS - 2008 CRF450R

    by Back2-2 » Thu Apr 18, 2019 3:27 pm

    "This one is always thinking he is...."

    Ok while I agree that you could in theory install a potentiometer to adjust the ignition curve, I think that it would have to be a
    micro-potentiometer to have the fine adjustment span required to have any attempt at being useful. But, I think it would be incredibly hard to manually do that to any degree of success. I believe that the area in the span of use fullness would be incredibly small. That said, it would be an interesting to experiment and see how well it worked. Many bikes now have "Ride Modes" that adjust the power curve that adjust everything from fuel to ignition but that is controlled by a computer. Trying to be the computer is going to be tough. I found as many others have that on my YZF450 disconnecting the TPS actually gave a better linear power delivery than the TPS. I have never disconnected my TPS on the CRF450 to try it but that is always an option.
    Neil
    Black Hills of SD
    Life without Motorcycles would just be boring, really boring
    Honda 450X. Yamaha Tracer GT900. HD Fat Boy. Triumph Bonneville. Yamaha Majesty 400. Yamaha Grizzly. Yamaha Wolverine. Yamaha TW200
  • mframpton
    Posts: 17
    Joined: Sat Nov 25, 2017 10:39 am

    Re: Live mapping SPS and TPS - 2008 CRF450R

    by mframpton » Thu Apr 18, 2019 8:33 pm

    "This one is always thinking he is...."

    Ok while I agree that you could in theory install a potentiometer to adjust the ignition curve, I think that it would have to be a
    micro-potentiometer to have the fine adjustment span required to have any attempt at being useful. But, I think it would be incredibly hard to manually do that to any degree of success. I believe that the area in the span of use fullness would be incredibly small. That said, it would be an interesting to experiment and see how well it worked. Many bikes now have "Ride Modes" that adjust the power curve that adjust everything from fuel to ignition but that is controlled by a computer. Trying to be the computer is going to be tough. I found as many others have that on my YZF450 disconnecting the TPS actually gave a better linear power delivery than the TPS. I have never disconnected my TPS on the CRF450 to try it but that is always an option.
    Ha ha Guilty as charged. I do meddle a lot. I’ve got a guitar that I call FrankenStrat. It’s got so many mod options that I don’t think I could ever test all the permutations. But honestly I’ve got one setting that I like best and that’s where it stays. The CRF I don’t imagine will be any different.

    I agree. No way I could match what a DSP can do real time. Honestly what I’ll probably end up doing is simply wiring in a bypass switch for the Shift position sensor. And probably later maybe some character enhancements.

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