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1982 XJ650 Maxim Low power at high rpms

Discussion in 'XJ Technical Chat' started by Traye, Dec 8, 2019.

  1. Traye

    Traye New Member

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    I just recently bought a 1982 XJ650. I got it home and was riding down my street and noticed at high rpms it starts to bog down. Sometimes it would get up and go, other times only go max 35ish. I haven’t taken the carb apart yet. The guy I bought it from claimed to have just rebuilt it.

    side question. Any reason the vacuum line going to tank should be capped off, because it is?
     
  2. DaygloDavid

    DaygloDavid Active Member

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    Has the fuel cock (tap) been changed from vacuum type to gravity feed type.
     
    Jetfixer and Toomanybikes like this.
  3. Toomanybikes

    Toomanybikes Well-Known Member

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    I have seen some people run the bike on the PRI which is the prime position to bypass the vacuum setting.
     
  4. XJ550H

    XJ550H Well-Known Member Premium Member

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    make sure the vac port on the intake boots is capped off.
    could be the vent in your gas cap is clogged if you unlock it it will pop up a little then see if you bog down.

    or just clean it
    Your Gas Cap and You
     
    Last edited: Dec 9, 2019
  5. XJ550H

    XJ550H Well-Known Member Premium Member

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    I think you may have a slipping clutch. by the way you discribe high rpm low speed

    so when you are going 35mphish what is the rpm and what gear are you in.

    could be clutch cable needs lube or adjustment
     
  6. Ryengoth

    Ryengoth Active Member

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    "Bogging down" means the engine drops in revs substantially and loses power when you give it throttle. If you are seeing consistent revs with the throttle but losing -speed- then it's likely your clutch pack or the cable needs adjusting to let the pressure plate move in more.
     
  7. Ryengoth

    Ryengoth Active Member

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    My bike was behaving with both issues in the last ride video I posted. It won't run unchoked right now. It would bog down and die if I gave it throttle with the choke off. Also, when I'd give it throttle (choked) it would rev up great but I'd lose acceleration past 5mph increase or so each gear due to the clutch slipping. You could hear the bike winding up, see it on the tach, but no increase in forward speed(it was enough throttle to pull the bars up visibily but it didn't)

     
  8. mlew

    mlew Well-Known Member

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    Never believe what the PO says unless they have proof.
    Time to pull the carbs and go through them
     
  9. XJ550H

    XJ550H Well-Known Member Premium Member

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    n
     

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