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  1. #1

    Ultra 310, 61 mph, at 6400 rpms

    I donít know if itís appropriate to start a new post, because itís an addition/update to the one I had last year.
    Iím the one who flipped his jet ski in the ocean, and tried to go above and beyond by flushing it out, removing intercooler etc. and I inadvertently mixed one of the vent lines with a water line, pumped water in the engine, seized the cam, and locked the engine.
    I decided to rebuild the engine last winter, I was amazed at how many different areas I found this milky substance called oil. But the overall rebuild went fine.
    I was able to buy a slightly used head with valves, and cams.
    Piston couldíve been reused, but I was hearing many horror stories about the OEM 310 pistons cracking that I updated the pistons and rings to Riva.
    Some waviness on the cylinder walls, so I sent the block out for re-coating and a piston for resizing the bore.
    I took my time timing the cams, knowing itís quite easy to be off, re-verified a few times, the cam marks match.
    I had 70 hours on the ski, did the proper break in period per the manual, and have since accumulated 8 hours on the ski. From 0-60mph it runs amazing, I raced another Kawasaki ultra 310 and beat him off the line every time. The throttle cable can be fully open, but only up to ĺ open does the ski react, the last quarter the ski doesn't react.
    Top speed, 61 mph, at 6400 rpm, with boost (dashboard) of 13ish.
    After the break in period I notice an exhaust leak at the manifold, I thought that was the issue, it wasnít. Cleaned seating services, replaced with all new gaskets.
    I disassembled the supercharger belt tensioner, the pivot pin was seized, fixed it, rotates easily with two fingers, still the same speed.
    Fuel flow is around 6-7 ounces, per the 3 seconds.
    All clamps seem secure, no additional liquid or spraying in the compartment, no codes, Iíve done an oil change, no evidence of water in the oil. Intercooler is clean, compression is fine and exhaust filter and spark plugs have been changed. New head gaskets, and supercharger belt.
    I do have a scom installed.
    I think I need the big guns for this oneÖ..

  2. #2

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    Quote Originally Posted by NCski View Post
    I don’t know if it’s appropriate to start a new post, because it’s an addition/update to the one I had last year.
    I’m the one who flipped his jet ski in the ocean, and tried to go above and beyond by flushing it out, removing intercooler etc. and I inadvertently mixed one of the vent lines with a water line, pumped water in the engine, seized the cam, and locked the engine.
    I decided to rebuild the engine last winter, I was amazed at how many different areas I found this milky substance called oil. But the overall rebuild went fine.
    I was able to buy a slightly used head with valves, and cams.
    Piston could’ve been reused, but I was hearing many horror stories about the OEM 310 pistons cracking that I updated the pistons and rings to Riva.
    Some waviness on the cylinder walls, so I sent the block out for re-coating and a piston for resizing the bore.
    I took my time timing the cams, knowing it’s quite easy to be off, re-verified a few times, the cam marks match.
    I had 70 hours on the ski, did the proper break in period per the manual, and have since accumulated 8 hours on the ski. From 0-60mph it runs amazing, I raced another Kawasaki ultra 310 and beat him off the line every time. The throttle cable can be fully open, but only up to ĺ open does the ski react, the last quarter the ski doesn't react.
    Top speed, 61 mph, at 6400 rpm, with boost (dashboard) of 13ish.
    After the break in period I notice an exhaust leak at the manifold, I thought that was the issue, it wasn’t. Cleaned seating services, replaced with all new gaskets.
    I disassembled the supercharger belt tensioner, the pivot pin was seized, fixed it, rotates easily with two fingers, still the same speed.
    Fuel flow is around 6-7 ounces, per the 3 seconds.
    All clamps seem secure, no additional liquid or spraying in the compartment, no codes, I’ve done an oil change, no evidence of water in the oil. Intercooler is clean, compression is fine and exhaust filter and spark plugs have been changed. New head gaskets, and supercharger belt.
    I do have a scom installed.
    I think I need the big guns for this one…..
    damn, seems like you covered a lot ...13 pounds if definitely low....maybe reset the computer and unplug the Scom ??

  3. #3
    I forgot to mention, shortly after break in period I took it to the dealership to have the valves adjusted. So I can't say 100% that the cams are timed correctly, if it was off a tooth or two would I see it out of the hole too, or more at top speeds?
    If not, I'm leaning towards air, anything I can check in the throttle body, waste gate, super charge besides leaks, and how would I detect leaks at idle in my driveway? Again, 3/4 of the throttle is responsive, the last 1/4 I really don't get any reaction out of the ski.

  4. #4
    Take the time to smile sirbreaksalot's Avatar
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    Check the T/B insulator to manifold.
    Only takes a slightly rough hand to tear it

    Waz

  5. #5
    Another update, it runs rougher it hesitates, lower rpms, anD speed, but has the same boost 14, when I first take it out, until it warms up

  6. #6
    "just sayin".. jetdave56's Avatar
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    Ultra 310, 61 mph, at 6400 rpms

    A quick check all 4 wire coils and spark plugs seated..?

    Since this was a rebuild and was running fine before flip something was put back incorrect or loose though you seem to cover everything ... retrack your steps..

    I think what SirBreak means is the additional damper( connection ) on the intake manifold to TB that was deigned for the 310s new intake manifold ..they've been known to break or crack creating boost leak ,might be hard to see..

  7. #7
    FOUND IT, after fixing the belt tensioner, and checking fuel flow, fuel pressure, fuel injectors, exhaust leak, compression test, leak test, computer check, intake manifold leak, timing.....
    It was the pulsing coil, runs like brand new!

  8. #8
    steffi69's Avatar
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    Quote Originally Posted by NCski View Post
    FOUND IT, after fixing the belt tensioner, and checking fuel flow, fuel pressure, fuel injectors, exhaust leak, compression test, leak test, computer check, intake manifold leak, timing.....
    It was the pulsing coil, runs like brand new!
    You said that your issue was the red coil who give to the spark plugs ?


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