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  1. #1

    Join Date
    Jul 2011

    GP1300R engine rebuild

    First I want to say Hi to you all, First post after some months of reading.

    Im a Swedish rider and bought me a Gp1300R -04 for some months ago.
    Directly I discover that it took in water and start of with some repairs and fixes.
    (It was the intake duct how has ripped the inserts out from the hull)

    Did go with DIY pump tunnel reinforcement also but some extra in bottom of the hull, repair after the inserts.
    Sealed the pump shoe.
    Also went for premix.
    R&D ride plate
    R&D 1200 Intake

    Had fun one month, and then one evening it just died, took and start it up again and it seems like it ride as normal, maybe I lost some rpm.
    Ride with it the next day and it died again. This time it didn't ride so good afterwards, max 4300 rpm. Ride it in to my trailer and took it up.
    Made an compression test and zero on the third cylinder. (the rearest one)
    Has not have the time yet to put everything apart, but guess that piston is totaly fried.

    So now to my questions. The machine has 135 hours, shall I go for a total rebuild, pistons, cylinder, rod, crank?
    Or top end is enough. Of course look if crank and rods are okay first.
    Then witch parts shall I go for, stock or some nice aftermarkets?
    Some other things that will help to keep the dependability higher?

    Also thinking about going free flow on the exhaust, my friend has an GPR1200 can we switch waterbox with each other witout any power lost on his craft?
    Read that the 1200 box should be better with FF on 1300.


  2. #2
    It really depends on how bad it is inside. Obviously a full rebuild is better, but a top end is cheaper. Hell my 760 blew up, we dumped the metal shavings out of the motor, threw a top end on it, and this is its second season running strong so sometimes you can get away with it. As for changing your waterbox or the ff don't bother. You'd not making enough power yet to warrant it. If you want to spice things up get yourself a fuel controller and have the head milled to 150 psi compression and do a nice rebuild. After that slap on a dynafly and you'll be happy. Oh and make sure you have waveater clips on your powervalves!

  3. #3

    Join Date
    Jul 2011
    Has ripped it apart today, didn't look nice. What do the expert think has happend? Is it a power valve catch?
    This is the third cylinder
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    The other cylinders and pistons had some scratches also but not so deep as third. Probably possible to hone. Experts on piston wash can take a look at the other two, I will have it to that they has gone little lean?
    Click image for larger version. 

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    Then my head look like this, is it repairable?
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    I'm pretty impressed that the craft did 50km/h in 40 minutes back to the trailer location.

    I will probably go for a complete rebuild now, don't know yet if I shall bore to 1390 and maybe a high compression head.

  4. #4

    Join Date
    Jan 2006
    Texas City, Texas
    Quote Originally Posted by SweRider View Post
    .............. and then one evening it just died, took and start it up again and it seems like it ride as normal, maybe I lost some rpm. Ride with it the next day and it died again..........

    When you pull the cylinders, you will have a better idea about wether or not to do a full rebuild. As bad as the head looks, a machinest may be able to salvage it, recut and reshape the domes and still get you to a conservative compression range of 150 psi. You will save a lot of money going that route rather than getting an aftermarket one. Make sure you get with someone who knows about these engines though. The head will need a specific cut to minimize detonation at that compression.

    You are on the right track of what to do, generally speaking, but I wanted to offer some advice for the future about 2-strokes that I think is just as important.

    Sometimes 2-strokes will give a hint of a problem, and in your case the hint was that it died for "no apparent reason". As a rule, once a 2 stroke begins to go bad the only thing that happens is that it get worse faster and faster. The more you ride it the faster it goes bad and the cost to repair increases.

    If a symptom that you cannot identify immediately appears, the best thing to do is to shut the boat down, put it on a trailer and try to figure what the problem is. This may have started out as a mild seizure or a little detonation due to bad gas that could have been easily repaired. Instead, it quickly accellerated into something really ugly and expensive.

    The more you ride your boat the more in tune you get with how it operates. My gut tells me that this sort of thing will happen from time to time, and this philosophy of not riding even to the point of towing it in to minimize damage has served me well through the years. Yeah, it is inconvient, but it sure saves money,time, and grief in the long run.

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