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  1. #1
    ADDDDDDAH DDDDDAH DDDDDAH!!!!
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    ultra 150 engine trouble

    whats up all. i have a buddy who just picked up an ultra 150. i do alot of work/maintenance on my yamaha and some of my buddies boats as well. ive got a few hour invested in this thing and still havent any solid finds yet.
    ski starts and runs but idles really rough. bottom end response is flat but seems to clear up over 2500 rpm. did a comp test all 3 around 110psi. thought it was clogged idle circuit. no such luck. new reeds and all intake gaskets. i was running it on the hose today with airbox off looking for possible vac leaks and such. I noticed when i cupped my palm over carbs only front carb would suck my hand down. center and rear carb have little or no vacuum. Cracked cases or bad crank seals a possibility??? Any help would be huge. thanks in advance>>Paul "Buy yamaha!!"


  2. #2

    Motor

    Check the bottom of the cases for a hole. Its common for a piece of the skirt to punch thru the case but the motor to still run. Look for metal in the bilge.

  3. #3
    ADDDDDDAH DDDDDAH DDDDDAH!!!!
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    ughhh.. just as i suspected. can these be repaired easily?

  4. #4
    btldigger's Avatar
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    So are you saying it has a hole punched out the bottom?

  5. #5
    Skiworx's Avatar
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    Give us a call..

  6. #6
    ADDDDDDAH DDDDDAH DDDDDAH!!!!
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    update

    yanked motor and tore it down. no internal damage or case defects. Just lose bolts on case halves!! Does anyone recommend a certain sealant for mating cases. i usually use red gel seal similar to what mercury uses on their powerheads. i noticed some type of white sealant used on previous rebuild?? Anyone know what this could be?? Im also contemplating whether to install new piston and ring at this point. cylinders are in great shape. Puff hone and new set?? or just reassemble the old junk???hmmmm..

    PS> if anyone knows something else that i might have overlooked please let me know.Although im sure lose case halves could be my initial cause im still not convinced ive located the original problem here. thx Paul

  7. #7
    btldigger's Avatar
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    For sealant use 1211 or yamabond would be fine. Use blue loctite on all the bolts. You havent said how many hours were on it but i would probaby do the top end.

  8. #8
    ADDDDDDAH DDDDDAH DDDDDAH!!!!
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    not sure on the hours. clock is reading 65hrs but cross hatch with no ridge up top. piston skirts have very little wear. I was more concerned about good ring seal than anything else. Comp was around 105-110psi just prior to tearing it down. Do you know where these things should be when theyre fresh?? thanks really appreciate all the feedback

  9. #9
    btldigger's Avatar
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    65 hours isnt bad. With stock heads they usually have 110-115 psi a/m or cut stock heds it could go as high as 150 on pump gas.

  10. #10
    Quote Originally Posted by hooksgp1300 View Post
    yanked motor and tore it down. no internal damage or case defects. Just lose bolts on case halves!! Does anyone recommend a certain sealant for mating cases. i usually use red gel seal similar to what mercury uses on their powerheads. i noticed some type of white sealant used on previous rebuild?? Anyone know what this could be?? Im also contemplating whether to install new piston and ring at this point. cylinders are in great shape. Puff hone and new set?? or just reassemble the old junk???hmmmm..

    PS> if anyone knows something else that i might have overlooked please let me know.Although im sure lose case halves could be my initial cause im still not convinced ive located the original problem here. thx Paul
    What do the bolts look like that hold the case together? I found an unidentified bolt about an inch or so long in the bottom of my hull earlier this season. I looked like heck to try to find where it came from but never did fine it. Can case bolts in a bone stock, never been worked on motor work themselves out?

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