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  1. #1

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    GP1300R rear cylinder detonation?

    I had a customer bring in a 03' 1300R that has very low hours "44" that had almost no compression in the rear cylinder. After pulling the head I found the rear piston was melted down to the ring only on the exhaust side. The ski is stock besides wave eater clips and a riva D plate. After looking for a possible cause I checked the spark plugs and he had put BPR8ES not BR8ES-11 in it. The question is would just the different plug with the same heat range cause this type of failure?

    I know I can replace the rear piston/cylider and the ski will run fine but just don't want it to do it again.


  2. #2
    Duke's Avatar
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    Plug change isn't going to do that.

    Do you know why the D-Plate was installed?? Its possible the Cat failed and pieces are blocking the waterbox causing too much back pressure.

    Also, sometimes the ring will catch the exaust valve and cause the ringland to break making it look like deto.

  3. #3

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    The D plate and clips were installed to prevent and future problems to as a repair.

    The other two cyliders look fine with no sigs of detonation or running hot. The rear clinder and head were coated with the grey film like finely ground up aluminum and oil.

    I am leaning to either a crankshaft seal air leak or a problem with the fuel injector for that cylider. Do the injectors ever have a problem by not being used often and get cloged and not provide enough fuel to the cylinder?

    I will post a picture later of the top of the piston.
    Last edited by dank; 06-03-2008 at 07:29 AM.

  4. #4
    Duke's Avatar
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    Could be a clogged injector, couple of places to send them out and get checked. Maybe fuel went bad??

    Doubt its a seal leak with that many hours but it wouldn't hurt to do a pressure test. If you do a search there are several links on how to pressure check the motor.

  5. #5
    Do the injectors ever have a problem by not being used often and get cloged and not provide enough fuel to the cylinder?


    Yes, have the injectors ohm checked, cleaned and flow tested. This should be an annual maintenance on all EFI skis.
    The only pre-injector fuel filter is a sock/screen at the fuel pump pickup. Whatever passes thru that will get caught at the injector screen at the injector inlet. Any crap in the fuel system will always go to the rear injector and cause problems there.
    To have 3 injectors cleaned, flowed, with a flow measurement of each one is usually around 80 bucks.. Cheap maintenance, and then you KNOW..

  6. #6

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    I ordered the parts for the top end rebuild and am going to send all three injectors to RC to have cleaned and checked. I will put the best one on cyl #3 to help. I also talked with the customer and the fuel was over a year old and was 89 octane when he put it in.

  7. #7
    Duke's Avatar
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    Quote Originally Posted by dank View Post
    I ordered the parts for the top end rebuild and am going to send all three injectors to RC to have cleaned and checked. I will put the best one on cyl #3 to help. I also talked with the customer and the fuel was over a year old and was 89 octane when he put it in.
    Bad fuel could be the culprit and may have clogged injectors as well. I'm not an EFI guru but if there is a pickup screen on the fuel pump it may be wise to give that an inspection.

  8. #8

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    Ok, will do. It should be easy to get out once the pipe is out tof the way.

  9. #9
    Happily Self-Employed WFO's Avatar
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    It probably spun a ring. Seen a bunch of them here lately.

    Also better check the crank for phase. Seen a couple out.

    Upgrade the headgasket to 05-newer one. Better cooling for #3.

  10. #10

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    Do you know if the SBT head gasket has the cooling update? That is where I normaly get my gaskets from.

    Not sure if spinning a ring would cause it to melt away part of the top of the piston down to the ring land.

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