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FX140, compression, cylinderhead, all ok?

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  • NiklasES
    PWCToday Newbie
    • Aug 2014
    • 5

    FX140, compression, cylinderhead, all ok?

    Hi all. Hope you all is doing well in these crazy times.

    I need some help to figure this out, and hopefuly put my mine to ease.

    I try to keep it short. I have rebuilt a FX140 MR-1 engine with 109 hours on it. (one new piston, rings, gasket etc) and when i bought it i was told that it had a newly rebuilt cylinderhead.
    But when i put it all togehter and start it up, i had an ticking noise (wrote a thread about it here).
    So what i did was leave it a shop so see whats wrong.
    And no, the pistonhead was not rebuilt. What he did was re-shims all the vaules.
    And told me, - Run this was this summer, and see that everything works as it should. I would like to take a look at the hole cylinderhead later, it was alittle wear on one cam, and it was the exhaust valuve that wasent good. (that one he fixed/shimed)

    I did run it for about 5-6 hours this summer. And all well. No worries.
    I recently got another child, so it got very limited time a the garage. So i figured.. If it works well now, why would i need to put it apart and leave it. (he had the hole ski last time). Some time and money.

    What i did now was a compression test, i figure this would be a good thing to do to see how the vaules are doing.

    This is my results
    1# 160 psi
    2# 170 psi
    3# 165 psi
    4# 155 psi

    These are very low, yes.
    192 psi is what the manual say is good, and 157 is minimum. No more the 14 psi between cylinders. BUT, the ski has been sitting for 3 months now, and i did it "cold".
    So i think these number would go up? With abit of running. Question is, how much?
    Also borderline on the 14 psi note.

    Also checked the spark plugs. #1 was abit more black then the others, but all and all, they dident look to bad?

    (note: these sparkpluggs has been in since day one. So they are the same as when it ticked. Maybe thats explain why the #1 plugg looka abit diffrent?)

    Now to the main question.
    I really just wanna use this ski now and enjoy it.
    Do you think i should be happy with this or do need to contiue worring that all will fall apart eveytime im out there
    Did talk to some other people that i know, that are good with engines and they say. If it worked for 5-6 house. Your good. Dont worry about it. But still, need your opinion on this.

    Thanks for taking your time.

    /Niklas
    Attached Files
  • Myself
    PWCToday.com Is My Home Away From Home
    • Jun 2006
    • 7767

    #2
    Re: FX140, compression, cylinderhead, all ok?

    Compression is probably fine, your gauge is likely off a bit. It's common to see wide variation on one that's been sitting for a while.
    http://www.facebook.com/twinlakesjetskirepair

    '89 Kawi 650SX 42.4 GPS
    +3" stock pipe, ported ex. manifold, drilled waterbox, blueprinted pump, Ocean Pro ride plate

    '99 Yama GP1200 65U 61.8 GPS
    ported cylinders, matched cases, milled head, blueprinted pump, long ride plate

    '96 Seadoo HX 717 53.13 GPS
    light porting, massaged cases, lightened flywheel, port matched manifolds, Rossier pipe, stubby pump cone

    Comment

    • NiklasES
      PWCToday Newbie
      • Aug 2014
      • 5

      #3
      Re: FX140, compression, cylinderhead, all ok?

      Originally posted by Myself View Post
      Compression is probably fine, your gauge is likely off a bit. It's common to see wide variation on one that's been sitting for a while.

      Your right. I did see that the pressure was dropping. So i find two leaks. I did manage to fix one. And got alot better results.

      1# 175
      2# 175
      3# 170
      4# 165

      And this with still one leak. So i think its good.
      That tells a newbie like me that the cylinderhead is good, also the valves.

      So, why would do i need to disable the cylinderhead an have it looked at, or rebulit. If it all works good?
      Last edited by NiklasES; 12-22-2020, 03:52 PM.

      Comment

      • Myself
        PWCToday.com Is My Home Away From Home
        • Jun 2006
        • 7767

        #4
        Re: FX140, compression, cylinderhead, all ok?

        I don't know, you would need to ask the mechanic that suggested it.
        http://www.facebook.com/twinlakesjetskirepair

        '89 Kawi 650SX 42.4 GPS
        +3" stock pipe, ported ex. manifold, drilled waterbox, blueprinted pump, Ocean Pro ride plate

        '99 Yama GP1200 65U 61.8 GPS
        ported cylinders, matched cases, milled head, blueprinted pump, long ride plate

        '96 Seadoo HX 717 53.13 GPS
        light porting, massaged cases, lightened flywheel, port matched manifolds, Rossier pipe, stubby pump cone

        Comment

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