1. Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

Xj700x swap into xj700 frame

Discussion in 'XJ Modifications' started by Harry frunkin, Jul 5, 2022.

  1. Harry frunkin

    Harry frunkin New Member

    Messages:
    4
    Likes Received:
    1
    Trophy Points:
    3
    Location:
    Usa
    Hello everyone. For the past 6 months, I have been struggling with my XJ700 (air cooled). It never seems to run right. I have put new piston rings in it and bought 2 different carb racks because the one the bike came with was held together with zip ties and home improvement screws. I finally gave up trying to fix it after replacing pretty much every part on the bike, and I bought a running XJ700X (water cooled). The problem is that the 700x has a bent frame, but everything else is fine. The reason I am here writing all this is because I want to swap the Genesis motor into my air-cooled frame, but I don't quite know the fastest and most effective way of doing that. Any and all insight would help greatly.
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

    Messages:
    13,199
    Likes Received:
    3,854
    Trophy Points:
    113
    Location:
    Great North Woods
    stripe down the x and transfer harness asds well as everything else onto the 700 frame you may have to do some welding for some brackets unless the frame has a place to bolt rad to it.
    that would be if the motor fits in the frame. measure mounts
     
  3. Simmy

    Simmy Well-Known Member

    Messages:
    2,261
    Likes Received:
    1,126
    Trophy Points:
    113
    Location:
    Waterloo Ontario Canada
    Looks like the frames are pretty much the same, except as @XJ550H has suggested, a few small differences for the water cooling.
    The best way to go about this is to strip both bikes down to the bare frame.
    With a Dremel remove any tabs you need from the X frame then weld them to the N frame.
    Start now, take your time and you will be ready to ride it next spring.


    700N frame.png

    700X frame.png
     
  4. Simmy

    Simmy Well-Known Member

    Messages:
    2,261
    Likes Received:
    1,126
    Trophy Points:
    113
    Location:
    Waterloo Ontario Canada
    thinking about this a little more, with the differences being so slight,
    you probably just need to strip the motor and steering stem out of the way on the N.
    All your tabs will be right at the front of the frame, weld them on and touch them up with black paint.
    If you're not after a full on restoration you could do this pretty quick.
     
  5. Harry frunkin

    Harry frunkin New Member

    Messages:
    4
    Likes Received:
    1
    Trophy Points:
    3
    Location:
    Usa
    Thank you for your reply. So far I have removed the motor and wiring harness from the air cooled maxim. After starting this swap I realize this is going to be easier than I anticipated with just some minor welding and tab relocation. I'm going to be swapping the maxim X forks and rear suspension over next and will update this thread with any progress "if I remember".
     
    k-moe likes this.
  6. Harry frunkin

    Harry frunkin New Member

    Messages:
    4
    Likes Received:
    1
    Trophy Points:
    3
    Location:
    Usa
    Just tore the maxim X apart today found out the front of the frame is wider than the air cooled. Now I'm stumped i can't use the maxim X frame and if I try cutting it in half and welding it to the air cooled frame I'd be moving VIN numbers around.
     
  7. Simmy

    Simmy Well-Known Member

    Messages:
    2,261
    Likes Received:
    1,126
    Trophy Points:
    113
    Location:
    Waterloo Ontario Canada
    Is it wider to accommodate the fan?
     
  8. Huntchuks

    Huntchuks Well-Known Member

    Messages:
    951
    Likes Received:
    395
    Trophy Points:
    63
    Location:
    East Rochester, NY
    I just checked and the front, top motor mounts both measure 11.25 in. to the outside of the triangle mount adapters (stays). 1985 X and 1986 airhead.
     
  9. Simmy

    Simmy Well-Known Member

    Messages:
    2,261
    Likes Received:
    1,126
    Trophy Points:
    113
    Location:
    Waterloo Ontario Canada
    I guarantee the motor will fit. I suspect the frame might be wider just below the steering stem to accommodate a fan in there.
    Still puzzled that the N has the removable frame rail from the X
    It is only needed to fit the taller 5-valve head motor.
    If Yam built a frame specific to the N and made narrower frame (at fan mount) why would they bother with the removable section?


    When I put the X motor into my XJ650 Seca frame the valve cover needs to come off to fit.
     
    Last edited: Jul 15, 2022
  10. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    The airheads AND the X Have the removable frame section
     
  11. chris dahl

    chris dahl New Member

    Messages:
    5
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    8804 231st st sw edmonds wa.
    please let me know if you want to sell the xj700x engine
     
  12. Huntchuks

    Huntchuks Well-Known Member

    Messages:
    951
    Likes Received:
    395
    Trophy Points:
    63
    Location:
    East Rochester, NY
    When I bought the X it was missing one of the nuts/bolts from that section. Replaced. When I tore it down for the valve job I noticed they were missing again. I think I'll use some blue on it this time.
     
  13. Harry frunkin

    Harry frunkin New Member

    Messages:
    4
    Likes Received:
    1
    Trophy Points:
    3
    Location:
    Usa
    I ended up just restoring the maxim X after waiting 8 months for all the title transfer stuff to come in. Now I have an xj700 air cooled paper weight sitting in my shop but I'm thinking I might put a harbor freight predator motor in it.
     

Share This Page