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XJ750 Engine.....'square' in Frame

Discussion in 'XJ Technical Chat' started by kerriskandiesinc, Jun 13, 2018.

  1. kerriskandiesinc

    kerriskandiesinc Active Member

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    Seems very odd, and I've only just noticed, but motor looks to be about 1/4" 'out' over to the left hand side, while ridden.......carb tops too ( although I guess that COULD be wrong order of intake boots??)

    I've measured the engine in the frame,( tape measure, not EXACT) and it STILL seems 'off' to frame spars......maybe by about 1/4" front/to back, like it's twisted, back seems LESS 'out of line', frame bolts, engine bolts, engine/frame large rear spacer all present and correct, and tight .......should i loosen everything and see what happens?

    Bike runs straight and true.....well, maybe pulls to the left a little ( camber, i think would count for this??)

    But you can take your hands off the bars at 90MPH, and part form a slight tendency to wander left......there are NO wobbles, no uneven tire wear....apart from usual 'camber' wear.......should i be concerned, overly concerned or just ride the thing, lol !!.....>Guess i should check F/R wheels for alignment, yes??

    No, I have never had the motor out, and even if I had, i've had these motors out many a time, never (to my knowledge) 'twisted' one!!!
     
  2. k-moe

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

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    I would strongly suggest checking the frame for straightness.
     
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  3. kerriskandiesinc

    kerriskandiesinc Active Member

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    Without removing a ton of stuff......easiest way, you can think of???
     
  4. Polock

    Polock Well-Known Member

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    I'm glad that worked out for ya
     
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  5. kerriskandiesinc

    kerriskandiesinc Active Member

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    :D
     
  6. k-moe

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

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    Use a chalk line to snap three parallel lines on the garage floor that have the same spacing as the lower frame tubes and the backbone (you might be able to just use one line if you're not confidant in making three parallel lines. since that can be tricky). Center the backbone over the middle line (you'll need to have the fuel tank removed). Be aware that the rear wheel is not going to be inline with the front, even if the frame is perfectly straight.
    You can eyeball it for straightness, and/or use a framing square and ruler to take measurements of the frame tubes relative to the chalk lines.

    There is probably a better way than that, but I just don't know what it is.
     
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  7. kerriskandiesinc

    kerriskandiesinc Active Member

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    Thanks!!!!...
    If by some miracle the F/R wheels are aligned, I'm leaving it alone, lol !!!!
     
  8. k-moe

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

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    But they aren't supposed to be aligned. If they are in alignment because of a bent frame or bent swingarm, then the rear tire will not be rolling straight (it will crab).

    That she wants to pull to the left is a concern. Even considering the road crown, she should want to run straight.

    Keep in mind that there are other factors that can cause a motorcycle to pull to one side. Among them are a dragging brake caliper, loose swingarm, misaligned fork legs (very common, so I'd actually check this first), notched steering bearings, and probably a few other things I'm forgetting.
     
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