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  1. #1

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    1300 Upgrade to 1390 - Questions?

    I am considering this upgrade of my '03 1300 to a 1390. I have added a few things to have a 80 mph ski. Just wondering the cost and what I could expect with regard to performance. I do not want to give up reliability, but just wondered what performance gains I could expect? What are the downsides? Thanks in advance for any help.


  2. #2
    WATER WOODY's Avatar
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    check pm.

  3. #3
    txgp1300r's Avatar
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    great mod....if in doubt bore it out.....quicker and faster..mid range pull is where it rips.....down side is premium fuel only and waiting for your riding buddys to catch-up (unless the got big bore also)....dont cut corners, use new welded crank,etc

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    Altezza01's Avatar
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    listen to woody...he has 2 BB monsters

  5. #5
    JetSkiDaddy's Avatar
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    Quote Originally Posted by txgp1300r View Post
    great mod....if in doubt bore it out.....quicker and faster..mid range pull is where it rips.....down side is premium fuel only and waiting for your riding buddys to catch-up (unless the got big bore also)....dont cut corners, use new welded crank,etc
    + 1
    I love my 1390. I usually pack some stuff to make a sandwich while I am waiting for my buddies to catch up

  6. #6

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    Appreciate the replies. Just wanted to see if there was a downside with regard to reliability. With my current ride, TJ has done the cylinders and I currently use 93 pre-mix. My set-up has been turn key and I didn't want something that I would have to be worried about. Anything else besides cylinders and heads? I have had the current crank welded. Thanks.

  7. #7
    philip_gpr's Avatar
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    if you already have a TJ ported 1300 then the gain to going to a 1390 isn't all that large - I would even suggest it is not worth the expense

    it is about a 7 % displacement gain, maybe 10 - 15 hp, so maybe 2 mph

  8. #8
    Altezza01's Avatar
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    this is you're best bet.....get yourself a set of 1200 cylinders and use those for 1390. you gonna have to get them bored and bigger pistons anyways. and after you have everything sell your tj ported topend. and pocket the money. you also have to get part of the case grounded down for clearence.

  9. #9
    Happily Self-Employed WFO's Avatar
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    I can get my hands on some 1390 cyls... plated, ported, and ready to go

  10. #10
    Hydrotherapy's Avatar
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    Quote Originally Posted by WFO View Post
    I can get my hands on some 1390 cyls... plated, ported, and ready to go
    non pv's

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