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  1. #1
    Avi8tor's Avatar
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    Ported EFI ski What did I do wrong here? Bad injector? Water? Air leak? opions please

    I bought this ski a few weeks ago and on test drive it ran perfect. It is scary fast so only went about 65-70 part throttle on it but the guy I bought it from took for spin and went over 80 on gps. I rode it a couple times and ran super strong in with redlight on riva controller, but below 50mph seemed blubbery rich. Only had about 20 hrs since fresh pistons and ported cylinders. Maybe I shouldnt have messed with it but I changed the head with one from osidebill to raise compression to 145 psi new plugs and ran it yesterday with controller set to 7776 and it seemed to run great. I was all excited even did a few short full throttle blasts to best of 80.7 mph I was grinning ear to ear ! (put about 45 miles on it) On the way back it messed and had greatly reduced power. I limped home last 4 miles and motor sounded fine ( no knocking or clanging just weak)

    SO I pulled the head off and below pics is what I found. 1 and 2 look very rich but number 3 scorched it and head chamber was very clean. Powervalve still moves up and down and cylinder had been renikasilled with great pattern still on walls. I used a brand new headgasket with all shims and light coat of grease on it before installing.

    Could a bad fuel filter or injector caused this? Air leak? water intrusion? detonation? or did I messup somehow?
    #2 Click image for larger version. 

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ID:	278879 #3 Click image for larger version. 

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ID:	278880 cylinderhead wasn't damaged. Click image for larger version. 

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    It was raining when I took it apart in yard and the waterdroplets on the head and gasket I think are just from where raining. I didnt notice any water in cylinders when first removed.


  2. #2
    Yamaha artisan Cutlass's Avatar
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    First thing that comes to mind when I see a burn through hole in the middle of a piston is a loose spark plug causing an air leak and a lean hot spot.

  3. #3
    Moderator OsideBill's Avatar
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    Quote Originally Posted by Cutlass View Post
    First thing that comes to mind when I see a burn through hole in the middle of a piston is a loose spark plug causing an air leak and a lean hot spot.
    Ditto I had this happen once, was the spark plug tight? I put spark plugs in with my torque wrench after that experience, 18 ft-lbs

  4. #4
    Moderator OsideBill's Avatar
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    In the picture of the head, that is #3 with the ding correct? is that how the gasket came off with it? The reason I ask is the tab on the gasket that hangs out the side should be on #3 cylinder exhaust side. If it was installed backwards it may have affected your cooling.

  5. #5
    THE PLATE MAN JIM'S PERFORMANCE's Avatar
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    that is definitely a lean condition hole in the piston, either not enough fuel to that cylinder maybe an injector issue or an air leak because the other cylinders look good.

  6. #6
    Avi8tor's Avatar
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    The sparkplug was tight , I had to loosen with a wrench before removing it. ... here is a picture of the head, I do not see any dings, may have been the camera angle. The headgasket I looked at both sides when taking pics this morning and may have just laid it up there incorrectly. Here is how it was installed, in this picture is how it was installed.
    Click image for larger version. 

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  7. #7
    Avi8tor's Avatar
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    Quote Originally Posted by JIM'S PERFORMANCE View Post
    that is definitely a lean condition hole in the piston, either not enough fuel to that cylinder maybe an injector issue or an air leak because the other cylinders look good.
    I really thought the engine running JUICY JUICY Obviously I was wrong but was thinking had it running way on the safe side. I adjusted the fuel controller to 4 on circuit 2 and it ran smooth, so I kept richening it up to 7 cruising at 50 ( yellow light on) EGT temperature dropped over 100 degrees and it picked up a rich little burble in exhaust and which is how it ran for last 20 miles or so. The egt only reads cylinder 2 and was it was rich as the wash showed. Too bad I didnt have one on #3


    So thinking is perhaps injector or air leak? What things should I be looking at for leak since it was so isolated to #3?
    I do not know so forgive if dumb comment, does anything of it look like water intrusion as cause? Have injectors been known to cause this problem?
    Do appreciate the inputs

  8. #8
    Moderator OsideBill's Avatar
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    The head looks fine, the first pic looked like there was some damage.

    The gasket has a tab on it, that tab should hang out on the exhaust side. In your latest picture it is facing the intake side. are you sure this was correct?

  9. #9
    Avi8tor's Avatar
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    Will this work as a pressure tester? Using a radiator pressure tester with sparkplug adapter (#3 is already well ventilated) , pull throttle bodies and block holes then put piece of solid gasket paper where exhaust manifold meets jacketed waterpipe ( 4 bolts) and pump up to 10-15 psi?

  10. #10
    Moderator OsideBill's Avatar
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    Another question, did you add washers under the head bolts like we discussed?

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