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  1. #1

    Lean No 3 Cylinder almost BANGGGGGGGGGG

    Hello Chaps

    Please see pictures of my 04 GPR no 3 Cylinder.
    Last year 2006, i replaced my Head gasket to a Single layer one to bost compression .The ski is fitted with 3x Riva 45psi heads.
    I ran the ski on a lake without the seat on, so i could adjust the controller accordingly i left it where i got max RPM and top speed. The boat was quick, i recall on one of the runs the engine shut down, and it ran like a dog, i noticed i had no lights on the EFI controller, After about 30- 45 seconds the enging shut down again, i restared and all was fine, to play safe i increased the fuel by one didget on the EFI. The boat was fine, i put the seat on a ran it with no problems.

    i thought i would play safe for 2007 and put the double thickness head gasket back on and used the modified 2006 head gasket. i have increased the efi again by one on the fuel ( not tested yet)
    Could this be LEAN on the low speed fuel circuit.

    I know the cylinders are well cooled as each has its own cooling line to each cylinder, and the water flies out of the pissers rather than a trickle

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  2. #2
    #3 is not lean, it's rich with all of that wash and no carbon. I'm much more concerned with #2, that looks lean. I'm also concerned with your motor just shutting off, signs of a seizure.

  3. #3
    Moderator RX951's Avatar
    Join Date
    Apr 2005
    League City, Texas
    * Did you do a compession check B4 you pulled the head off ?
    * How do the cylinder walls feel ?

    Also, becareful running 1 layer of headgasket.
    Last edited by RX951; 01-21-2007 at 11:51 AM.

  4. #4
    Hydrotoys's Avatar
    Join Date
    Jul 2005
    Mesa, AZ
    I read on here last year about grounding issues on the ignition box causing this. Check the installation for grounding issues.

  5. #5
    WATER WOODY's Avatar
    Join Date
    Aug 2005
    Minden, Nevada, United States
    1 & especially 2 are lean.Like hydro sais,i would check your ground wire on the EFI unit.What was the compression before you took the heads off? What do you mean 45psi heads? You mean 145 psi? What are your EFI settings?

  6. #6
    All three cylinders were 150 psi no damage, scrapes to wall etc they feel lovely and smooth
    Last edited by yamahajetpilot; 01-21-2007 at 01:41 PM.

  7. #7


    Excuse my ignorance why are 1-2 lean, where are you looking on the cylinder for this i thought it was no 3,

    The discolour you can see, is where i applied carb claener to clean the gasket mounting surface off, both 1 and 2 are nice brown colour, except dead centre where plugs ignites on top, The spark plugs are perfect.

    As i said earlier i have reverted back to a 2 pecice head gasket

  8. #8


    The heads are 145cc domes, not variable chamber heads that are normally used on stage 2, i have had varible chambers before changeing to these

    EFI settings were 1-3-1-3
    Last edited by yamahajetpilot; 01-21-2007 at 01:51 PM.

  9. #9
    Last pot settings , the rpm switchover to high speed is at 5,400rpm i watched this on my pet2500 tach
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  10. #10
    Hydrotherapy's Avatar
    Join Date
    Sep 2006
    The Rock
    #3 is rich same as all three of mine, i posted pics and half a dozen of the best on here said rich but ok..
    i am no expert but your e.f.i settings seem way off only telling you what info has been past on to me but a good start point for e.f.i with the modds you have must be in the same ball park as my

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