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  1. #11
    I dream skis
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    Re: crank seals, right?

    Quote Originally Posted by Seadoo timebomb View Post
    When carbs were apart, did you actually run something thru the jets? Or just blow them out with air or cleaner?

    Dried fuel residue will not wash off. Jets dont need but a thin film to cause an obvious lean condition.

    Another common problem with that series motors is rotary valve clearance. The intake manifold gets scraped by rotary valve every time piston is on the down stroke. Very little bit of wear outside of factory clearance will make the engine run poorly.

    There are several tale tale symptoms from your description to not having any power and dying when put in water.

    It can easily be a combination of the two. That makes things more difficult to diagnose correctly.

    I am going to assume you are reinstalling the airbox with stock flame arrestor mesh each time.

    Those 657 motors are extremely reliable and ran well in their day. If ski has not been abused, neglected or someone not knowing what they are doing, will run forever.
    The more I think about it, the more I like RV clearance as a culprit. One thing I have noticed is I can feel some turbulence if I hold my hand near the carb through while running, like air is getting pushed back out the carb. I know the RV timing on the 657x is pretty aggressive and wasn't sure how normal this was, could be that it holds the valve open until the case starts getting pressure.

    The good idle has kept me from seriously considering this, but case pressure at idle should be pretty minimal and I can see a leak back out the RV being a major problem once the engine tries to rev.

    I'll yank the carbs again and check the clearance.

    If it is bad, what is the best way to address? I'm not close to a machine shop that would be familiar with doing this and don't really want to roll the dice that they understand what I am asking them to mill and how much.

    I see SBT seems to sell these, is that a reliable option?
    1992 750SX with mods
    1991 X-2
    1996 SS

    I have more skis than friends.

  2. #12
    Resident Guru
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    Re: crank seals, right?

    You should be able to feel some pulsing thru the the carbs when cranking or running. That pressure is what pushes rotary valve against the cover and wears out. The longer intake timing the more pulse you feel.

    I still think you have fuel related issues. But without first hand knowledge, I can only make uneducated guesses.

    I used to cut a bunch of those manifolds. Each time a different way. Should have spent some time making a fixture. Would have saved a bunch of time.

    SBT sells remans with exchange. Likely your best bet, But only AFTER you confirm it is the problem, not just assuming.

  3. #13
    Resident Guru
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    Re: crank seals, right?

    Quote Originally Posted by newsance View Post
    I put in a new needle and seat as part of the carb rebuild and would have put an oring on there if the old needle/seat had one.

    If needle and seat were leaking, I'd be troubleshooting a rich condition right? I'm very confident I am dealing with a lean condition off idle.
    The brass seat that needle fits in has a small oring. They all do. Can you add some more information to what you actually did?

    The low and high speed adjustable needles also have orings. Both places can cause major issues.

  4. #14

    Re: crank seals, right?

    Could your pulse line be clogged/split.. I'm no expert but same motor had a split in the line that I couldn't see and it would run bad at mid throttle, at higher rpms it seemed fine.. when you take the cap off the gas tank does it seem to have pressure?

  5. #15
    PWCToday.com Is My Home Away From Home kcr357's Avatar
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    Re: crank seals, right?

    Quote Originally Posted by newsance View Post
    I put in a new needle and seat as part of the carb rebuild and would have put an oring on there if the old needle/seat had one.

    If needle and seat were leaking, I'd be troubleshooting a rich condition right? I'm very confident I am dealing with a lean condition off idle.
    The oring isnt optional. If you have/had a lean condition, you have an additional problem too, due to not having an o ring
    How many gerbils could a gerbil jammer jam if a gerbil jammer could jam gerbils?


    "You build cheater motor's & still get smoked !!!!"
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  6. #16
    PWCToday.com Is My Home Away From Home kcr357's Avatar
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    Re: crank seals, right?

    "If needle and seat were leaking, I'd be troubleshooting a rich condition right? I'm very confident I am dealing with a lean condition off idle."
    Not if someone tried jetting it to run without an oring in the seat.
    Pull the carbs and check the jet sizes, check the popoff, and the hi lo screw orings.
    How many gerbils could a gerbil jammer jam if a gerbil jammer could jam gerbils?


    "You build cheater motor's & still get smoked !!!!"
    "Its not your fault. You just don't understand what you're talking about. "

  7. #17
    I dream skis
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    Re: crank seals, right?

    Quote Originally Posted by kcr357 View Post
    "If needle and seat were leaking, I'd be troubleshooting a rich condition right? I'm very confident I am dealing with a lean condition off idle."
    Not if someone tried jetting it to run without an oring in the seat.
    Pull the carbs and check the jet sizes, check the popoff, and the hi lo screw orings.
    Almost all of this I put into my first post.

    Jets are verified to be stock. In addition, I know I am the first person to go into this carb because I was breaking the paint on the screws loose. I do not have a tester to check popoff, however, I did reuse the stock springs (which I know are stock as nobody had opened the carb before), and verified the spring pressure feels very similar. I stated that I confirmed lows and high settings were correct in my initial post.

    Despite my initial musing when asked, I am now 100% certain that I put the new seats in with an o ring. I noted that the old seats had an o-ring, and I remember the new seats fitting snugly before the screw holding them in place was put in, which means I o-ringed them. And again, a leaking needle and seat would result in a rich condition.

    I appreciate the rotary valve sealing point by a previous poster and hope to check the gap this week as that is the top of my list of suspicions at this point.
    1992 750SX with mods
    1991 X-2
    1996 SS

    I have more skis than friends.

  8. #18
    I dream skis
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    Re: crank seals, right?

    Quote Originally Posted by cleetus View Post
    Could your pulse line be clogged/split.. I'm no expert but same motor had a split in the line that I couldn't see and it would run bad at mid throttle, at higher rpms it seemed fine.. when you take the cap off the gas tank does it seem to have pressure?
    Good thought but no. I replaced the pulse line when I replaced the fuel lines.
    1992 750SX with mods
    1991 X-2
    1996 SS

    I have more skis than friends.

  9. #19
    PWCToday Regular Old man rookie's Avatar
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    Re: crank seals, right?

    Not sure if I misread or just missed it, did you set your pop off pressure or just use the old spring?

  10. #20
    I dream skis
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    Re: crank seals, right?

    Quote Originally Posted by Old man rookie View Post
    Not sure if I misread or just missed it, did you set your pop off pressure or just use the old spring?
    used stock springs after doing some basics to at least confirm they do not appear messed up. I know they were stock, I confirmed they were both the same length, that they offer similar compression pressures. Also compared to new springs in the kit, but installed the old ones as they appeared serviceable and I didn't want to induce another variable.

    I realize that this could potentially be an operability problem, but again, worn out springs causing low popoff would mean rich, and I am chasing lean, so I am not looking too far into this being my problem.
    1992 750SX with mods
    1991 X-2
    1996 SS

    I have more skis than friends.

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