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  1. #1

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    Dropped valve carnage pics: Amazingly not bad at all!!

    Our story begins once upon a time, in a lake not so far away . I was riding along about just cruising at 5-6k when all of a sudden the power just fell out. I could immediately tell from the exhaust note, and engine sound that I was only running on 2 cyl's. Luckily I was only a few hundred yards from the marina, and was able to drive it back to the marina, and onto my float lift without it dying. I started by checking the plug connections, fuses, basic stuff, re-assembled and tried to start it. But it just wouldn't restart no matter what I tried. I then pulled the plugs which all looked good. I turned it over with no plugs in it, and it sounded fine, and I could see all cyl's were moving so at least the bottom end seemed ok! I then moved onto compression test, which I did with my index finger lol. I could immediately feel that there was near to no compression in the middle cyl. I really wanted to know what was going on, and having exhausted all other possible causes I could think of, I was prepared to pull the head right there. But once I got the valve cover off, it was immediately apparent what had happened.

    Check out that valve!! That is freaking fantastic!! It didn't break into pieces, or snap at the stem, it just bent! That's what I'm talking about! From here on out, I'm sold on 08+ valves. I believe they finally fixed any weaknesses in the valves.

    Well, as I stated in the title turns out a broken retainer caused an intakie valve to drop. I take full responsibility for the failure as I was running rotax racing alum retainers, (thinking they were Ti ) and didn't do my 20hr checks. So I had a retainer weaken on me, and split in two right down the middle. This then released all pressure holding the valve up, at which point it dropped into the combustion chamber where it was promptly smacked the piston (only once! ). The piston hit then lodged it back into its seat folding the valve into an S shape, and breaking the the valve guide, which actually held the valve just on the edge of piston clearance!! Upon disassembly of the motor to change the head and inspect the bore, etc... I found what I believe was the REAL cause of the failure. The cam chain tensioner spring had either broken, or was binded up. Because it was locked about 1/2 way compressed! After realizing this and inspecting the camshaft, I believe this slack in the valvetrain/cam chain is what caused the retainer to break.

    With slack in the cam chain, my timing will start to get sloppy, and I could be up to probably 10 degrees off in either direction at any time. This slack in the chain also causes the rockers to slam into the cam at the ramp point, and consequently smack the valve stems. So instead of the smooth tight valve movement you usually have in a roller rocker motor like this, I had sloppy slamming valve train. One would have thought I would have heard this happening, and would have heard a ticking from my motor. But who knows, I somehow missed it.

    Check out the pics though. I got about as lucky as someone can get when they drop a valve. No cyl wall damage, extremely minimal piston damage, and even the head isn't bad! The valve seat even still looks perfect!! This happened about two weeks ago, and I already swapped the head, and am back on the water. After typing this though, I just realized I should probably have broken the motor all the way down, and changed the cam chain as well. I'll have to do that ASAP.

    I suppose the lesson I learned from this is it is probably a good idea to step back every so many hours of riding (20-30?) and give everything a good once over. It takes less than a minute to remove, inspect, and re-install the cam chain tensioner, and if I would have caught that, I probably wouldn't have had an engine failure.. Maybe

    Sorry for the length of this story, It got a little longer than I had intended, but wanted to share.
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  2. #2

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    Pics of camshaft wear marks.
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  3. #3
    Site Admin Green Hulk's Avatar
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    Ouch! You got real lucky Chris. It could have been much worse.

  4. #4

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    Quote Originally Posted by Green Hulk View Post
    Ouch! You got real lucky Chris. It could have been much worse.
    You can say that again!!!!

  5. #5
    State of Confusion BartenderSmalley's Avatar
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    Quote Originally Posted by boostaholic View Post
    You can say that again!!!!

    What engine?? I have a CAM from an '04 GTX/SC that is just sitting around doing nothing.

  6. #6
    Jarrett's Avatar
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    Glad it wasn't worse for you. The 08-09 valves are supposedly stronger? How do you know this?

  7. #7
    Ride Hard! aha's Avatar
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    Wow thats pretty incredible!

  8. #8
    ROTAX RACING performance
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    the valve retainer are stronger in 2008/2009

    the valves are the same in 2006/2007/2008

  9. #9
    Site Admin Green Hulk's Avatar
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    Quote Originally Posted by mrracing View Post
    the valve retainer are stronger in 2008/2009

    the valves are the same in 2006/2007/2008
    Good info Malte. I didn't know that about the 08/09 retainers.

  10. #10
    Richieb's Avatar
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    Valve probs were solved in 07 production as I understand.

    Anyway... Naaaaaaaasty bed-time story ya got there.

    "Darkness looms in ev'ry cylinder.
    "The valve train ghoul is close at hand..
    "And though you rev to keep her moovin'..
    "The engine starts to shudder..
    "For no mortal Seadoo can resist the horror of the...
    ".........VALVE DISASTER....

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