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  1. #21
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: ts77r hole in piston

    Any thing to update?
    Horsepower == Speed, RPM != Speed



  2. #22
    Frequent Poster Associated98's Avatar
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    Re: ts77r hole in piston

    Ah, well the hull is nice and clean . Not really, iv been fixing a snowmobile these past few months. Hull is stripped of most remaining parts, engine is lubed and put away, hull is waxed and in storage now, never did get the flywheel off. But I'm not giving up on it. Just waiting and collecting parts over the winter for next spring.
    Last edited by Associated98; 11-12-2016 at 01:46 AM.
    Own:
    99' TS770R
    98' TS1000R
    97' Daytona 1000
    Owned:
    94' Montego (my first) sold
    95' Daytona sold
    95' Daytona parted out
    95' Barracuda sold
    96' Montego sold
    96' Daytona (the one that got away...) sold
    96' Monte Carlo 900 sold
    97' Daytona 1000 clean and beautiful. You will be missed.

  3. #23
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: ts77r hole in piston

    Quote Originally Posted by rdjeep View Post
    Lean-outs are caused most times by air ingestion passed bad seals. Time to do soup-to-nuts on this one, or you'll just repeat history.
    Most 2-stroke watercraft have main seals that leak vacuum all the
    time. It is when the springs fall off the main seals and they leak pressure,
    that is when noticeable carburetor problems occur, and most people ride
    their ski's like that for a considerable length of time before they bring it
    into a shop.

    Quote Originally Posted by hemmjo View Post
    A couple of issues I see from reading this thread.

    #1) A leak in the MAG side crank seals, would not melt the PTO piston.
    Agreed!


    IMO that PTO piston seized at least 5 times, maybe 10 or more. The
    MAG piston probably seized when it was the only cylinder that was
    still running. Sounds cruel to ride a ski while it is running on only one
    cylinder, but people do.

    Because of the scaring all the way down the piston skirt, and the pattern
    on the piston and cylinder, I believe it started as water ingestion. It is
    very possible that water was being sprayed from the drive line into the
    PTO carb and to a lesser degree the mag carb.

    Look at picture #4. That is water damage on the MAG piston intake skirt.
    Now look at picture #1, the MAG piston has a heat seizure. See the
    difference?

    Now look at the PTO piston, it is much worse, but similar to the MAG
    piston's intake skirt. At some point, the PTO piston could no longer
    act like a bearing surface along the cylinder wall, and at that point
    it didn't matter how much oil was in the gas, and the seizures got
    worse.

    After any piston seized a few times, it causes a feather edge to
    develop along the piston crown. Also as that PTO cylinder lost
    compression, the load on the engine increased, cylinder heat increased,
    and it may have detonated, but it certainly preignited.

    When the spark plug bridge over-heated it caused preignited under the
    spark plug, and melted a hole in the piston. Before the spark plug bridge
    over-heated, the feather edge on the piston crown became hot enough
    for the fuel to self ignite, and it melted the piston crown.

    Detonation destroys, Preignition melts.

    You need to inspect, or rebuild the crank because of all the aluminum
    debris inside the big-end rod bearing, and the main bearings.



    Bill M.
    Last edited by wmazz; 11-28-2016 at 05:56 AM.
    Horsepower == Speed, RPM != Speed



  4. #24
    Frequent Poster Associated98's Avatar
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    Re: ts77r hole in piston

    Thank you for your advice wmazz Im definitely going to look into a few different things now. When i get the ski all back together ill try to make something to keep water from possibly entering the carbs as the thought of that scares the hell out of me. I am actually starting to look at just buying a different, running engine and plopping it in. I also started to work on my ski again. I finally got that damn flywheel off. Ended buying a brand new puller and black hardened bolts, using an impact to tighten it, heated up the flywheel, and used a can of computer duster upside down to spray the tip of the crank behind the bolt i was using for the puller. Used the impact some more and pop! Off she came. Now i can finally do pressure test on the motor. I am suspecting at least some sort of leak from the mag crank seal as the oil left a snail trail right to the seal. Money is tight at the Moment but i will try to update as soon as i find or fix something. Thanks for your patience and help!
    Own:
    99' TS770R
    98' TS1000R
    97' Daytona 1000
    Owned:
    94' Montego (my first) sold
    95' Daytona sold
    95' Daytona parted out
    95' Barracuda sold
    96' Montego sold
    96' Daytona (the one that got away...) sold
    96' Monte Carlo 900 sold
    97' Daytona 1000 clean and beautiful. You will be missed.

  5. #25
    Frequent Poster Associated98's Avatar
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    Re: ts77r hole in piston

    Im looking to purchase a set of carbs for my tsr, none of the part numbers on ebay match the part number on country cat for the carbs i need, but i cant tell on country cat of it is only one carb, or the carb assembly including the linkages and top plate for the flame arrestors. Its also my under standing that all of the 770 carbs regaurdless of the model they where installed on are identical, with only differences being jetting. So could i buy any set off mikuni 770 carbs and just re-jet for my tsr? Thanks guys.
    Own:
    99' TS770R
    98' TS1000R
    97' Daytona 1000
    Owned:
    94' Montego (my first) sold
    95' Daytona sold
    95' Daytona parted out
    95' Barracuda sold
    96' Montego sold
    96' Daytona (the one that got away...) sold
    96' Monte Carlo 900 sold
    97' Daytona 1000 clean and beautiful. You will be missed.

  6. #26
    PWCToday Guru
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    Re: ts77r hole in piston

    For what it is worth.

    The carbs on my 98 770TSL are 38's with fixed high speed jets and an accelerator pump on the rear one that is plumbed to both carbs.

    From the '99 service manual I have, it seems the 99 770R had dual 38's, while the 99 770L had a single 40. The 98 770L had dual 38's

    I bought a pair of 38's from a guy here. He was not sure what they were from, he thought they were from a 770 but was not sure the year. I got them just because they were not too expensive and I wanted the piece that holds the pair together on top and the flame arrester attaches to.

    These look close BUT, they have adjustable high speed jets, and no accelerator pump. So you have to be a little careful what you get. Are you looking for used or new?
    Last edited by hemmjo; 03-25-2017 at 07:50 PM.
    2, 1998 TS 770 L, restored and running great. (Except for the one with engine that SBT put the WRONG crankshaft bearing into and is now sitting as I collect repair parts)

  7. #27
    Frequent Poster Associated98's Avatar
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    Re: ts77r hole in piston

    Definitely used, country cat wants a grand for the carb(s) and i dont even know if comes with both, the diagram only shows one carb. I just always compare part numbers before i buy a part to make sure it works. You would be suprized the number of times i come across two identicle looking parts, but theu have different part numbers which means something is different between the two.
    I know it uses twin 38s and if i remember correctly it does have an accelerator pump. But each model has a different part number... Go figure. Thanks for insight though, i was unaware some had fixed high speed needles.
    Own:
    99' TS770R
    98' TS1000R
    97' Daytona 1000
    Owned:
    94' Montego (my first) sold
    95' Daytona sold
    95' Daytona parted out
    95' Barracuda sold
    96' Montego sold
    96' Daytona (the one that got away...) sold
    96' Monte Carlo 900 sold
    97' Daytona 1000 clean and beautiful. You will be missed.

  8. #28
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: ts77r hole in piston

    Quote Originally Posted by Associated98 View Post
    Now i can finally do pressure test on the motor. I am suspecting at least some sort of leak from the mag crank seal as the oil left a snail trail right to the seal.
    It is normal for watercraft to have a vacuum and or pressure leak on
    the front main seal. Most leaking main seals will cause just carburetion
    issues like hard starting and a lean low speed (pilot) screw.

    Real problems don't occur until the tension springs have fallen off the
    main seal. Even when that occurs, the engine will not seize. It takes
    other problems in addition to a major vacuum/pressure leak for a seizure
    to occur.

    I know this because I tested front main seals on Kawasaki's while they
    were running for nearly 20 yrs.



    Which carbs do you have? SBN or SBN-i (seadoo style). Either carb can
    be rejetted for better performance, even if there is no high speed adjust-
    ment.

    In fact, the 800 full mod X2 I tune, has no high speed adjusters.


    Bill M.
    Last edited by wmazz; 03-26-2017 at 03:23 PM.
    Horsepower == Speed, RPM != Speed



  9. #29
    Frequent Poster Associated98's Avatar
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    Re: ts77r hole in piston

    I know they are sbn 38s but past that i am unsure. Thats kind of what i was thinking too. Most of the pwc mikuni carbs that i have seen look pretty much the same reguardless of the brand of ski they where installed in. So you are saying that a major air leak would not burn down a motor? Im just about all set to pressure test, i just need a way to plug the square intake holes as i do not have an intake manifold yet.
    Last edited by Associated98; 03-27-2017 at 12:27 PM.
    Own:
    99' TS770R
    98' TS1000R
    97' Daytona 1000
    Owned:
    94' Montego (my first) sold
    95' Daytona sold
    95' Daytona parted out
    95' Barracuda sold
    96' Montego sold
    96' Daytona (the one that got away...) sold
    96' Monte Carlo 900 sold
    97' Daytona 1000 clean and beautiful. You will be missed.

  10. #30
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: ts77r hole in piston

    What I am saying is that an air leak is almost never the only cause.
    Seizures normally require a recipe or a list of things to go wrong.

    Unless you have no 2-stroke oil

    I have seen motocross engines run while their cylinder is loose and
    raised 1/4" above the gasket surface.

    I have seen tons of jet skis with the springs falling off the main seals,
    and their main problem was only carburetor related.

    Besides their is a difference between water damage and a seizure.

    Water damage will cause catastrophic failures if you ignore the symptoms.



    Bill M.

    You may very well have a vacuum or pressure leak, but the cause will still
    be water damage, and the repair will still include replacing the main seals.

    So why pressure test it? BM.
    Last edited by wmazz; 03-29-2017 at 04:21 PM.
    Horsepower == Speed, RPM != Speed



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