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Interchangeable engine components

Discussion in 'XJ Technical Chat' started by Joshua Preston, Feb 18, 2017.

  1. Joshua Preston

    Joshua Preston Member

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    I am new to these motorcycles. I have been wondering if the parts from the xj yiks engines are compatible with the different capacity engines? I.e. can you take a cylinder head from the 750 and put it onto the 650 or vice versa? I am just curious so let me know if I am completely crazy about that working.
     
  2. k-moe

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

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    FIrst question is why. What is your goal?
    Many parts can be interchanged, but not all parts can be interchanged without also changing other parts.
     
  3. Joshua Preston

    Joshua Preston Member

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    I am on the hunt for a replacement cam retainer/cap. The yamaha dealer said that these were machined to the specs of the head it was manufactured with. My goal is to get a running bike at the cheapest cost. And I am finding more parts for the 750 engines than for the 650. So I was curious as to if they would be interchangeable. And what benifits or side effects would be caused by doing the swap. This is my first motorcycle. I have some experience with cars.
     
  4. k-moe

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

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    The Yamaha dealer is wrong about that. All the cam journals were machined to the same specification, as were the caps and head journals (The heads were line-bored with the caps in place). You should still use plastigauge to check for fit (clearnaces can loosen up due to wear), but you can grab a cam cap from any aircooled XJ. Just make sure that you get a cap for the correct position on the head.

    Now if you want a complete head, the XJ650 and XJ750 heads are identical. The only functional difference is which cams are fitted (and the cams are interchangeable, and this is why you can just snag a replacement cap if you want to).
     
  5. Joshua Preston

    Joshua Preston Member

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    Ah that was my concern. Thank You for the information.
     
  6. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    NOTE: XJ550 cam caps are unique to 550 (and maybe 600) engines.

    1980-81 (non-yics) cam caps are unique to those engines.

    1982-up YICS engines are unqiue (and can interchange).......EXCEPT for XJ1100 engines.

    XJ700-X and XJ750-X cam caps are unique to those engines.

    And of course XJ1100 cam caps are unique to those engines (probably the same as XS1100 caps, but have not verified).
     
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  7. k-moe

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

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    GAH I see missing characters from my post (I probably forgot to type them).

    Thank's to Chacal for posting clarifying info.
    I meant any XJ650/750 YICS, not just any old XJ.
     
  8. Joshua Preston

    Joshua Preston Member

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    That is what I figured since the yiks have 4 per cam where as the seca have 3. Now can you use the exhaust caps on the intake cam? Or are they different?
     
  9. k-moe

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

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    Same bore, but they might not swap. I've never tried.
     
  10. Joshua Preston

    Joshua Preston Member

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    Nice. I think I saw a set on ebay
     
  11. Joshua Preston

    Joshua Preston Member

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    The oil pan gasket is that the same for yics and seca?
     
  12. k-moe

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

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    The oil pan gasket is the same for all 650cc XJ models.

    Don't confuse YICS and Seca. YICS is an engine feature. Seca is the name of a sub-model (the sporty ones).
    YICS refers to a series of passages in the head and cylinder block that help improve combustion chamber swirl, and improve fuel mileage/ power. YICS engines can be found on both Maxim and Seca sub-models, as can non-YICS engines. Which you have will depend on engine size, model year, and which world-market the machine was originally built for.

    The easiest way to cross-reference parts is to go to an online parts fiche, and click the part number, then click the "used on" link to see all the models that part will fit.

    http://www.yamahapartsnation.com/oemparts/c/yamaha_motorcycle/parts

    You can also look through Chacal's catalog. It's a bit less handy, but more thorough, and contains much more information than I can provide here.

    http://www.xjbikes.com/forums/index.php?forums/xj4ever-supporting-vendor.23/
     
    Last edited: Feb 18, 2017
  13. Joshua Preston

    Joshua Preston Member

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  14. Stumplifter

    Stumplifter Well-Known Member

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    I wouldn't.
    Get them from Chacal. Chacal knows customer service and cares about getting you the right part.

    Trust and believe, you may save a couple bucks on eBay, but when you get the wrong part cause it doesn't match the picture and then you have to send it back and do another search for the right part . . . . That cost savings just went out the window through the price of frustration.
     
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  15. Joshua Preston

    Joshua Preston Member

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    I didn't see the cam caps listed on chacal's pages or I would have been more than happy to purchase them from him.
     
  16. Stumplifter

    Stumplifter Well-Known Member

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    Sorry.
    Dang, I guess he can't have everything.
     
  17. Joshua Preston

    Joshua Preston Member

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