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  1. #1

    higher quality crank bearings

    looking into rebuilding a very low hour fresh water 720. problem is the crank bearings went. motor turns over about seven or so revolutions then stops. turn the crank the other direction it frees up. then can rotate it again for a few more revolutions then it stops again. rotary valve is off so thats not the issue. top end is removed so its not piston related. only thing we can come up with is the bearings came apart and gather in the race on one side of the bearing and cause it to bind the crank.
    I do not want a sbt crank, they are junk. so are hot rods cranks. Just wondering if there is a higher quality bearing that can be put on an oem seadoo crank.

  2. #2
    Mark22's Avatar
    Join Date
    Sep 2009
    Springfield, MO
    I've got a 787 with a trashed out crank. I'v been doing a little research into buying the bearing the crank. (I'm a line mechanic at a factory, so I deal with bearings and such on a fairly regular basis) On the parts breakdown it tells you what the bearing numbers are. It is something like 6203 or 6306 or something along those lines. You can get that bearing from most industrial suppliers, the only problem is that they are not for engines. Engine bearings are noted with C3 which means that the inner diameter is slightly bigger than normal to make up for the rapid heat expansion in the engine. RS or 2RS means that it is sealed on one side or both. ZZ or 2ZZ (?) means that is shielded on one side or both. Places you could try, Grianger, MSC Industrial Supply, IBT Bearings, ect... Let me know what you come up with!

  3. #3
    If i knew,...I wouldn't ask sea-one's Avatar
    Join Date
    Aug 2009
    impressive"bearing" tip! I like it

  4. #4

    Join Date
    Sep 2009
    they're 6206 and 6207. probably the 2 most used bearings in the world. from machinery to aviation. the difference are determined by the suffix. different seal, grooves on the race, etc. why not just get them from sea-doo?I found that we used to use those two bearing on buses back in 1971 at work(searched parts database)but no longer, anyway I guess as long as you dont get "made in china" bearings,you'll be o.k.

  5. #5
    im going to ask marine crankshaft specialties about different bearings. they made me a custom v8 crank for me before and quality is amazing. also going to dig in deeper to learning more about crank bearings. Id like this engine to live for a while. currently factory pipe, water injection, westcoast head, 800 carbs with accelerator pump.
    while motor is apart will be getting cylinders and cases ported by group k. and a fresh set of rotax racing pistons in first overbore.

  6. #6
    Hydrotoys's Avatar
    Join Date
    Jul 2005
    Mesa, AZ
    Dumb question, but do you have the driveshaft disengaged from the engine? Possible pump binding or are you on the bench with this engine?

    The 720 was never that hard on the crankshaft or bearings. Somethings strange.

  7. #7
    dghal's Avatar
    Join Date
    Jul 2008
    League City Texas
    It must be a fluke they went out,,

    get new ones from Sea Doo and be done with it,,,,

  8. #8
    retro jet's Avatar
    Join Date
    Jun 2009
    New England
    Here is a link with a comprehensive catalog of bearing manufacturers. I have bought from them too.

    Unless there was a known issue or the Doo bearings are wicked expensive, I would give Sea-Doo's engineers the benefit of the doubt and buy what they spec'd. Thats not to say you can't find a bearing that is better suited for this application. If you want to make a project out of it, use the links found on the URL above, most mfg's have good articles, Timken and NTN for example.

  9. #9
    motor is on the bench. cylinders and pistons are out. so is rotary valve gear. only thing left is crank and rods in the case. no stator, statro cover or flywheel, or pto. so really pointing fingers at the crank bearings.

  10. #10
    Work Harder, Millions on Wellfare Depend On Us! ultramaxracing05's Avatar
    Join Date
    Aug 2009
    Beaumont, Texas
    might sound dumb but i got a 951 crank low hours that threw a rod, could i be able to sell it or get something out of it? seals are clean and bearings, i would hate to dump this crank

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