1. Some members were not receiving emails sent from XJbikes.com. For example: "Forgot your password?" function to reset your password would not send email to some members. I believe this has been resolved now. Please use "Contact Us" form (see page footer link) if you still have email issues. SnoSheriff

    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.

1981 seca 750 and 1986 maxim x 750. Same frame?

Discussion in 'XJ Technical Chat' started by Bryan Petruniak, Nov 2, 2016.

  1. Bryan Petruniak

    Bryan Petruniak New Member

    Messages:
    4
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Canada
    I was customizing a 1981 seca 750. When blasting the frame I found several weak spots.
    I have a 1986 maxim x 750 parts bike.
    I was wondering how similar the frames are?
    More so the motor mounts.
    Any help?
    Thanks
     
  2. Jetfixer

    Jetfixer Well-Known Member

    Messages:
    3,191
    Likes Received:
    1,501
    Trophy Points:
    113
    Location:
    Nothern Indiana
    I think frame is different..so mounts maybe as well.
     
  3. hogfiddles

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

    Messages:
    14,954
    Likes Received:
    5,238
    Trophy Points:
    113
    Location:
    near utica, new york
    They are not similar
     
    k-moe likes this.
  4. Toomanybikes

    Toomanybikes Well-Known Member

    Messages:
    2,836
    Likes Received:
    815
    Trophy Points:
    113
    Location:
    Tsawwassen bc
    If you have blasted the frame now is the time to repair and even gusset the frame in those weak spots, cut or add tabs for custom work that will look like factory finishes
     
    k-moe likes this.
  5. Quixote

    Quixote Active Member

    Messages:
    172
    Likes Received:
    35
    Trophy Points:
    28
    Location:
    Victoria, BC, Canada
    As others have said, the frames are quite different. Among other things, the front frame downtubes are different to accommodate the radiator on the X. But the motor mounting points are the same since the crankcases are basically the same. My guess is that mounting an aircooled 750 motor in the X frame would be straightforward but the rest of your Seca bodywork probably wouldn't fit. Also the Seca carbs won't match up with the X airbox.
    I mounted an X motor in a 650 Seca frame and the motor fit right in. It was the cooling system plumbing and carb manifold differences that have kept me tinkering for the last 25 years.
    If you are up for a challenge and you are doing a lot of customizing anyway, you could probably make it work. But if you are looking for a quick and easy swap, this won't be it. Far easier to repair the Seca frame.
     
  6. k-moe

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

    Messages:
    19,647
    Likes Received:
    6,756
    Trophy Points:
    113
    Location:
    The City of Seven Hills
    Thy are similar in that they are both motorcycle frames and both are made by Yamaha.
    Aside from the bare engine, none of the major components will swap over.
     
  7. Bryan Petruniak

    Bryan Petruniak New Member

    Messages:
    4
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Canada
    the motor swaped over. No problem
     
  8. Bryan Petruniak

    Bryan Petruniak New Member

    Messages:
    4
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Canada
    yes you are right. I just did it. Motor bolted right in. And it is nice to have the frame that unbolts with the motor.
    the rest of the bike is custom. so I don't need any of the other seca pieces.
     
  9. k-moe

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

    Messages:
    19,647
    Likes Received:
    6,756
    Trophy Points:
    113
    Location:
    The City of Seven Hills
    I hope that the custom part doesn't involve cutting up that very rare frame.
     
  10. Bryan Petruniak

    Bryan Petruniak New Member

    Messages:
    4
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Canada
    Actually it does. The frame was in rough shape anyway.
     
  11. Quixote

    Quixote Active Member

    Messages:
    172
    Likes Received:
    35
    Trophy Points:
    28
    Location:
    Victoria, BC, Canada
    Out of curiosity, which swingarm are you using (Seca or X)? As I recall the X had a larger diameter driveshaft and a larger u-joint. Be sure to check the driveshaft length as well. I'm not sure which one will fit the motor/frame combination best. I think the final drive gearing is different too (X had a 16 inch rear wheel, Seca is 18 inch).
     
  12. hogfiddles

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

    Messages:
    14,954
    Likes Received:
    5,238
    Trophy Points:
    113
    Location:
    near utica, new york
    Swingarms are the same.........
     
  13. Quixote

    Quixote Active Member

    Messages:
    172
    Likes Received:
    35
    Trophy Points:
    28
    Location:
    Victoria, BC, Canada
    Good to know. I only have a 650 Seca and a 750 Maxim X to compare (and they are different) but if you say that the 750 Seca is the same as the 750 Maxim X then there is no issue.
    I probably should have said 'final drive' rather than 'swingarm' because that's what I was wondering about. Is the final drive gearing the same in spite of the 16inch vs 18inch rear wheels?
     
  14. k-moe

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

    Messages:
    19,647
    Likes Received:
    6,756
    Trophy Points:
    113
    Location:
    The City of Seven Hills
    hogfiddles likes this.
  15. hogfiddles

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

    Messages:
    14,954
    Likes Received:
    5,238
    Trophy Points:
    113
    Location:
    near utica, new york
    the BIKES are different, but there are quite a few parts that are common to many models
     
  16. Quixote

    Quixote Active Member

    Messages:
    172
    Likes Received:
    35
    Trophy Points:
    28
    Location:
    Victoria, BC, Canada
    The u-joint is different. The driveshaft is different. Many of the other final drive parts are different. Feel free to look it up if you are so sure that I don't know what I'm talking about.
    Either u-joint (the larger X one or the smaller Seca/maxim one) will bolt up to the output flange on the engine but if you take the swingarm/driveshaft/final drive unit as a whole, you can't swap one for the other. I know this from personal experience. I'm not sure if the difference is a slightly different placement of the swingarm pivot in the frame or a slightly different length of driveline.
    I'm just trying to help out the original poster here. If he has both final drive units then one or the other will probably fit, but the other will not.
     
    k-moe likes this.
  17. hogfiddles

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

    Messages:
    14,954
    Likes Received:
    5,238
    Trophy Points:
    113
    Location:
    near utica, new york
    In my experience, the swing arms are interchangeable..... However---there is a difference in strength and gussetting from the 650/750 Swingarms ( no extra reinforcement) to the 700/X Swingarms ( extra U-shaped gusset).

    The final drives are interchangeable, but the gearing inside is a bit different.

    The driveshafts are different. The 700/X/900driveshafts are indeed thicker, as are the u-joints

    If needed, I can try to do a side-by-side comparo this weekend as time would hopefully permit

    Dave
     
    k-moe likes this.
  18. Simmy

    Simmy Well-Known Member

    Messages:
    2,478
    Likes Received:
    1,253
    Trophy Points:
    113
    Location:
    Waterloo Ontario Canada
    I'm really interested to see what you post Dave as I have the X motor in the Seca 650 frame but with the XJ700 16" rear wheel.
    Would I have identical final drive ratio to the X?
     
  19. hogfiddles

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

    Messages:
    14,954
    Likes Received:
    5,238
    Trophy Points:
    113
    Location:
    near utica, new york
    I don't know what the gear ratios are, I was just referring to Swingarms. I think Chacal would be the one to ask for ratios......thinking about it--that may be in the information overload section, but not sure
     

Share This Page