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XJ650 RPM Speed

Discussion in 'XJ Technical Chat' started by mlwistrom, Mar 19, 2015.

  1. mlwistrom

    mlwistrom Member

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    I have an 83 XJ650 Maxim and I do not have a tachometer. I have wired 2 different tachometers to the bike and they didnt work. The original tachometer worked but i removed the OE Instrument cluster because the speedometer basically exploded internally.

    Now to the point. Could anybody with a 650 Maxim let me know about what speed the bike will go in first or second gear around redline? I have been afraid to rev too high so I doubt that Ive even revved about 5000 so far.

    Also, is there any kind of rev limiter on these bikes to keep you from going over the redline?
     
    mlwistrom, Mar 19, 2015
    #1
  2. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    The only rev limiter is the engine dropping a valve. IIRC redline in first is somewhere around 45 MPH. What tachometers have yoy tried, and how did you wire them?
     
    k-moe, Mar 19, 2015
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  3. mlwistrom

    mlwistrom Member

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    i tried a couple of cheap tachometers off of ebay. They all had 3 wires on them but the OE tach had only 2 im pretty sure. They both had vague instructions on how to wire them and I tried every possible wire setup. But that needle never moved.
     
    mlwistrom, Mar 19, 2015
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  4. mlwistrom

    mlwistrom Member

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    Thanks for the speed info! It helped a lot!

    Anybody have any suggestions for a cheap tach that will work on an 83 650?
     
    mlwistrom, Mar 20, 2015
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  5. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    You already tried cheap tachometers. A inexpensive one that works is a used factory one. http://mikesxs.net has tachs that work on XJs, and Chacal probably does too.
     
    k-moe, Mar 21, 2015
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  6. mlwistrom

    mlwistrom Member

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    I would like to see if the one that I already bought could work. Ive tried wiring it several different ways but I couldnt quite get it. The wiring on this tach is shown in this picture: http://images.idealhere.com/lis/speedometer01.jpg

    Could anybody help me figure out how I would wire this. Ive never gotten the needle to move...
     
    mlwistrom, Mar 26, 2015
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  7. CapnRedbeard

    CapnRedbeard Member

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    Once you reach the power band in each gear you will no when to change up , that power band will pull right through till redline.
    Possible to fit second hand front cluster of the bay ??
     
    CapnRedbeard, Mar 26, 2015
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  8. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    The trouble with relying on hitting the powerband is that the engine keeps pulling hard well beyond redline; right up until the valves start to float. For longevity purposes that isn't a great way to learn where the shift points are (redline comes up fast once you get the engine on the cam).



    mlwistrom,

    based on your picture: Yellow (on tach) goes to Grey, Green (on tach) goes to Black, Black (on tach) goes to Brown. If that doesn't work then you probably have a faulty tach. The wires for the lights can go, Red (on Tach) to black, and Black (on tach) to grey, or you can tap in to the backlight circuit the speedometer.
     
    k-moe, Mar 26, 2015
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    mlwistrom likes this.
  9. mlwistrom

    mlwistrom Member

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    Thank you, I will give that a try when I have a day off of work!
     
    mlwistrom, Mar 27, 2015
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  10. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    I'd like to make a correction. It would be preferable to hook the backlight up to the same circuit as the speedometer's backlight. Depending on how the tach was made, the draw from the backlight might possibly cause enough voltage drop for the tach to not work correctly if you hook the backlight up to the yellow and green.
     
    k-moe, Mar 27, 2015
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