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  1. #1

    Is an EFI controller a must for a 2007 1300r if I add a mild head?

    The ski, a 2007 Gp1300 has 135psi all cylinders. I'm going to install a Lowell head @150psi.

    I've read thru the stickies and it's pretty clear the controller is a must.

    My question is, since Yamaha already tuned the timing etc to run this ski on 87octane(my ski runs worse with higher octane)

    I can get/run 93 octane. It seams to me that 6 more octane points against 15psi extra compression, should be plenty extra to keep it from detonating, etc..

    Ski has a D-plate(which is already cooling combustion), PPK, R&D1200grate, R&Dplate, stock prop. It does NOT have any intake filter mods, stock air box.

    Does anyone know who actually stocks the EJK controller. The company said 3 days to make one ($250 total).

    Any insights appreciated.

    In CT 85degree air, 73 degree water.

    EDIT: Just ordered an EJK controller, though still wondering.
    Last edited by GpaaH; 06-19-2015 at 11:33 AM.

  2. #2
    Prism's Avatar
    Join Date
    May 2007
    "New" Jersey
    Yes you need the controller. Yes you'll need to run super with that compression. No that will not be plenty to keep engine damage at bay. The engine tuning from the factory is on the edge in the mid range as it is. Not only do you need the octane when running 150psi, you need the extra fuel to tune out the lean spot which causes that stumble you're encountering and the extra fuel acts as a combustion chamber coolant. See what Lowell says.
    Last edited by Prism; 06-19-2015 at 01:15 PM.

  3. #3
    powerstroke specialist mikegp's Avatar
    Join Date
    Mar 2011
    Yes , yes , yes and a big yes!!!!!! , are you going to upgrade the prop? you need to

  4. #4
    Quote Originally Posted by mikegp View Post
    Yes , yes , yes and a big yes!!!!!! , are you going to upgrade the prop? you need to
    Geez Mike, no room for a "Maybe" in there.LOL

    I took the advice and ordered the EJK unit and have the Lowell 150psi head arriving same day.

    Correct me if I'm wrong anywhere..I also ordered a new wear ring with plastic insert and a DF 14/20. My concern is going slower on the bottom - lousy for small wake jumping.

    Despite doing the PPK kit i am getting somewhat of a lazy hole shot. It pegs to about 6000rpms, then hits 15/20mph and pegs at ~7000rpm. With my 250lb Butt, it Runs solidly up to about 64mph at 7200rpms.

    My 180 lbs kid does a mile or 2 more i believe. As a side note, my 2000 1200r with a PPK,head and a Skat beats this ski 3 or 4 boat lengths off the line - maybe slightly less after the PPK,grate.

    Thanks Guys! Thoughts?

  5. #5
    still kicking ass and taking names! Pale Rider's Avatar
    Join Date
    Oct 2005
    on the move
    also keep in mind when comparing your ski`s is the power valve engine VS the non power valve 1300. what you describe is the effects of the non PV 1300... But dial in that ski and it will walk the 1200...

    Prism is correct and gave great advise.
    Since your a big Lad, dial in the hull to get you going better, faster. PPK, stepped sponsons, leo`s hole shot filler, modified ride plate, maybe a drop nozzle for launching if you can find one, a ProTec steering nozzle with an 85mm ventui nozzle and also try the 87mm, and you`ll probably be tweeking the 14\20 for the sweet spot.

    lots of tuning and testing will give you the best results.

    good luck.

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