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Sport Jet 90 Piston Issue causes

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  • Sport Jet 90 Piston Issue causes

    Well not sure what happened here...any thoughts? Cylinder walls are good and oily, no sign of overheating, heard a loud clunk and then it died. The dealer thinks a ring may have caught on the exhaust port, but why would that happen...slop in the crank/rod/bearings? You can see the edge of the piston is turned up right at the exhaust port (lower left side). Could something have come loose in the crankcase and traveled thru the cylinder only to get caught on the exhaust port? Ugh! Nice gouges in cylinder wall too. Might be time to part it out.

  • #2
    Re: Sport Jet 90 Piston Issue causes

    I feel your pain (Tracker right) I'm taking my block to a shop on Sat to get an estimate on a bore/sleeve/weld job. Without the engine all we got is scrape aluminum it would seem.


    • #3
      Re: Sport Jet 90 Piston Issue causes

      Lots of newer parts: Mercury starter, Red Stator, trigger, switchbox, carbs rebuilt, jet pump/components all in good shape, flywheel is in good shape with all magnets in tact, original depth finder, trolling motor, trailer, maybe then some scrap aluminum! Last I heard the rebuild kit is about $700 (no machine work) and a rebuild is around $1800.


      • #4
        Re: Sport Jet 90 Piston Issue causes

        Crap, that is bad luck. My old 85XS Merc O/B jet popped a piece of piston skirt and it beat the hell out of the "top" of the piston and locked up. all in a matter of 2 seconds. Down home shop did mild bore on one cylinder, oversize rings and piston and back in business about 12 years ago. Still going when I sold it in July. I'd get some second opinions. Unless some internal problem you can't see, a single cylinder rework might fix it. Let us know if you figure out what caused it.


        • #5
          Re: Sport Jet 90 Piston Issue causes

          Sometimes if the rings get a bit worn, they start to spin around on the piston a bit. If the edge (open end) of the ring catches that exhaust port, you get those issues. Not much you can do except a rebuild. Hey...it's an imperfect world and things break. It's only a piece of machinery. Fix it or replace it.
          2001 Carver Voyager 374 'Stick's Competition'

          Something tells me I should be on the water....

          If I answer your upholstery questions, it's only because I've been doing it 20+ years...


          • #6
            Re: Sport Jet 90 Piston Issue causes

            no offense intended, i'm just saying without a very particular motor the botor is not worth much. Anyway here my estimate from the shop. $600.00 to resleeve 3 cylinders and weld all exahust port cracks (4 or 5 cracks total) so here it is as far as I can see.

            600.00 shop work
            750.00 rebuild kit on e-bay (seems to the most complete rebuild kit out there)
            80.00 trigger (I think it caused mine to blow)but maybe not I'm still lookin for another more reasonable cause.
            150.00 misc gaskets and shop supplys
            100.00 new head on e-bay (mine was pitted and am not taking the chance of reusing it)
            50.00 shipping of parts (maybe alittle more but not much I would'nt think.)
            1730.00 total (NO LABOR, I'll do it myself)
            2125.00 rebuilt shortblock (iboats)
            80.00 trigger
            100.00 misc shop supplies or gaskets
            110.00 shipping of block + any other shipping of gaskets and the like
            SO $685.00 diff for a pre rebuilt or a rebuild I do myself
            The rebuild I do myself at least I'll know what in it like .std pistons vs the .030 over **** that I got when I bought the boat. Obviously it had been worked over before I bought it and the bastard did'nt tell me. oh well buyer beware I guess.
            Hope this comparison help somebody.
            OH YEA, THANKS NO MORAL'S GUY FROM MORRIS ILL THAT I BOUGHT THE BOAT FROM if you read this. Sorry to everyone else.


            • #7
              Re: Sport Jet 90 Piston Issue causes

              Just curious as to how both of you have progressed, hopefully, to having boats again?


              • #8
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                Re: Sport Jet 90 Piston Issue causes

                well I'm still researching parts options, I'm down to 2 places for the rebuild kit. Maxrules.com or the one off of e-bay, seems like the one on ebay has the bearing cages wheras maxrules I'd have to buy them seperate a $162.00 or OEM at like $500+(there crazy i think). Nothing against MasterTech (I would rather buy from a marina then e-bay, just for the peace of mind) but when I'm trying to keep the cost down ebay shines. I know you pay for what you get so maybe would be making a mistake but got to roll the dice sometime. Has anyone here bought the kit from ebay?