SBT Jetski Engines, Parts & Accessories

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  1. #1
    Joined
    Jul 2004
    From
    South Georgia
    Posts
    8

    Default Success Of Rebuilds From the Top?

    Since this is my first experience with a piston failure I am curious as to the success of Top Rebuilds especially when it appears to be only a piston, and sleeve.

    I have a very strong mechanical background, and therefore recognize the importance of locating the cause.

    I don't mind investing a couple hundred dollars and a few hours replacing the destroyed parts verses a total replacement.

    What is the "rule of thumb", and/or vast experience with top rebuilds, and their worthiness?

    Thanks,
    JCH

  2. #2
    Joined
    May 2003
    From
    Houston, TX
    Posts
    372

    Default Re: Success Of Rebuilds From the Top?

    I don't know what the succes rate is, but if I had it to do over again, I'd go with a new SBT motor. Their 1 yr. no-fault warranty is unsurpassed. Obviously, you need to determine the cause of the problem and fix it - or you may end up toasting another motor. Good luck!
    "Helping you make smart choices about your money - so you can live a better life."

  3. #3
    Joined
    Jun 2004
    From
    st aug fla
    Posts
    35

    Default Re: Success Of Rebuilds From the Top?

    first thing you gotta do is pull the top end off and see how bad it is. if the piston came apart at all then it has contaminated the crank and you should not trust it. it is a rare thing for a watercraft engine to go without going all the way. here is a pic of an 1100 motor that was running (not very good)when i tore it down. wild huh
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  4. #4
    Joined
    Jul 2004
    From
    South Georgia
    Posts
    8

    Default Re: Success Of Rebuilds From the Top?

    I was lucky enough to have shut the engine down prior to severe damage though in pulling the cylinder box I know some debris has fallen into the crank housing.

    I am considering replacing the cylinder sleeve and piston assembly. Rod, and crankshaft retain their original color, and very minimal damage to the head.

    It appears to me as though this situation may warrant a top rebuild verses a reman even though I am a firm believer in starting fresh verses a patch job.

    Since I have 2 good piston, rings, rods, crankshaft, and head it seems wasteful to not at least try the piston/sleeve replacement first.

    I certainly do not wish to waste my time nor spend wasteful monies, but if top rebuilds in 65U Yamaha engines have good success ratio based upon minimal damage it certainly may be worth the effort.

    I recognize SBT is primarily in the business of selling remans, but I can't imagine SBT would recommend to replace verses repair under these circumstances. Obviously if the repair should be inaffective or troublesome I still have the opportunity to reman.

    Isn't it worth a try?

    Thanks,
    JCH

  5. #5
    Joined
    Jul 2001
    From
    Jacksonville nc
    Posts
    592

    Talking Re: Success Of Rebuilds From the Top?

    At this point the cases need to be split and the bearings on the crank inspected. If good them you can re-use the crank. I always split the cases to inspect the crank anything else is pure speculation. Always use new seals and gaskets.

  6. #6
    Joined
    Jun 2004
    From
    st aug fla
    Posts
    35

    Default Re: Success Of Rebuilds From the Top?

    i bet you play the lottery too if your heart is set on only doing the topend at least do all three holes. if not i will bet money that you dont get more than 10 hrs out of this patch job. if there is any head damage at all just think of the beating that rod bearing took. hate to sound so negative but you asked

  7. #7
    Joined
    Jul 2004
    From
    South Georgia
    Posts
    8

    Default Re: Success Of Rebuilds From the Top?

    John,

    No I don't play the lotto.....don't have to, but my impression of a top rebuild was just that, pistons, sleeves, and rings, therefore my question with respect to top rebuilds and their success seemed a valid question. I certainly understand my options with respect to a total breakdown, but why would I want to even consider the task since the reman option would be far less consuming.

    The boat is a new aquisition from an one owner senior adult who used it rarely. I had gone over most all systems prior to using same, but obviously there was something I missed. I suspect a lean carb, which showed up during my testing of the boat shortly after purchasing it. I shut down the engine as it began to drop rpms thereby minimizing catostrophic failure.

    I understand my choices:

    Top Rebuild
    Total Rebuild
    Reman
    Factory New

    This isn't a question of money, it is a question regarding when to do a top rebuild.

    Thanks

    JCH
    Last edited by JCH; 07-07-2004 at 07:00 PM.

  8. #8
    Joined
    May 2004
    From
    Orlando FL
    Posts
    102

    Default Re: Success Of Rebuilds From the Top?

    Top end rebuilds are fine. As long as your crank is ok and you don't need new crank seals, replacing piston and sleeve should be fine. The cause of 2 stroke failure if often an air leak , a clogged cooling line, or pre-ignition. Check out the technical article on piston inspection. It should help you find the problem. Don't be so paraniod.
    Never underestimate the power of stupid people in large groups!

  9. #9
    Joined
    Jul 2004
    From
    South Georgia
    Posts
    8

    Default Re: Success Of Rebuilds From the Top?

    Poser,

    Thanks for the reply, and encouragement. I suppose there are no guarantees in life, except of course with SBT. I'm not nearly as paranoid as I am curious.



    Thanks

    JCH

  10. #10
    Joined
    May 2003
    Posts
    517

    Default Re: Success Of Rebuilds From the Top?

    I'll put my 2cents in here.

    When I bought my blaster from a friend,I was new to the pwc world.He told me that he had done a top-end rebuild.And the ski ran perfect...but not for long.He stated to me that the lower corner of the piston was missing and that it probably blew out of the exhaust. 3 rides later she locked up.Rod bearing failure,snapped the rear rod.

    Now,having spent 5 years and many certificates in the bearing and PT business,I have been through many trainings as to the causes of bearing failures.The leading failure is due to contamination.It only takes one little spec of foriegn metal/sand to completly destroy a bearing.If you can imagine how a bearing works,it rolls on three surfaces.The surface of the roller,the inner race, and the outer race.One mark on any of these surfaces will leave a mark on the opposing surface,then the next,then the next,and so on and so on.

    My point is:If there is just one peice of anything left in you case,it will eventually get picked up into the bearing,causing damage,and eventually failure.And from the looks of the pics,there is alot of debris in that motor.

    As torquenut said,you must still completly disassemble the motor,and thoroughly clean and inspect everything(and lube bearings upon reassembly).However,you cannot actually see the bearing surfaces that I mentioned earlier,so they are rather impossible to inspect.But if you have any foriegh material in the bottom of the case,it has most likely made its way into the crank or rod bearings.

    On top of that,I also have 5 years experience in heavy duty mechanics.And have rebuilt every motor from 3cyl perkins to v8 detroit deisels.

    I have the original 701 in my shop(in pieces) atm,and am planning on rebuilding it,but it is getting all new internal parts...top to bottom.

    I am currently out of the mechanical field,and work for WeatherShield windows and doors as thier service and warranty tech for the west-central part of Florida.But still love to mingle with my own and friends mechanical problems.

    Hope that helps make your decision.
    Visit www.pwctoday.com for techical help

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