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  1. #1
    River Rat chevyll's Avatar
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    What’s the difference between GPR1300 & 1200 heads?

    I am putting a GPR1300 stock top-end on my 1200 bottom end. I have a set of Riva heads for my 1200 that I would like to use. My question is; Are the heads interchangeable? By rights the piston doesn’t extent past the gasket surface, at least on the outer edges. However Riva show two different kits. So are they different?



  2. #2
    My son (mohawk man) jeffsntx's Avatar
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    Yes they are different.

  3. #3
    OLD # 7 IEGPR's Avatar
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    For statrers the water jackets dont line up

  4. #4
    Happily Self-Employed WFO's Avatar
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    The water jackets will work, but the squish band is to narrow and the chambers are smaller

    ck pm

  5. #5
    Chrisrokc's Avatar
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    I am running a modded 1300r head on my 1200 to 1390 bigbore setup. You need to run extra washers (3 deep) to get the stock bolts to work. Other wise they will bottom out. Other than that grease the gasket and your set.

  6. #6
    mrbtd's Avatar
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    Quote Originally Posted by Chrisrokc View Post
    I am running a modded 1300r head on my 1200 to 1390 bigbore setup. You need to run extra washers (3 deep) to get the stock bolts to work. Other wise they will bottom out. Other than that grease the gasket and your set.
    Just buy 1300 head bolts next time. They are shorter.

  7. #7
    Chrisrokc's Avatar
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    Quote Originally Posted by mrbtd View Post
    Just buy 1300 head bolts next time. They are shorter.
    I am running 1300 head bolts. You still need 3 washersish because when the head is cut it makes it even thiner and the bolts will bottom out in the cylinders.

  8. #8
    Hydrotherapy's Avatar
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    Quote Originally Posted by Chrisrokc View Post
    I am running 1300 head bolts. You still need 3 washersish because when the head is cut it makes it even thiner and the bolts will bottom out in the cylinders.
    is it just a 1390 thing with head bolts as i had lowell cut my head and my stock bolts are fine with 4-5mm of thread left before they bottom out

  9. #9
    Chrisrokc's Avatar
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    Quote Originally Posted by Hydrotherapy View Post
    is it just a 1390 thing with head bolts as i had lowell cut my head and my stock bolts are fine with 4-5mm of thread left before they bottom out
    Ah! This could be true. I am not sure how much more he cuts the head down for the 1390.

  10. #10
    River Rat chevyll's Avatar
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    Thanks for the info.

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