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  1. #1

    How did this happen

    So a little background SBT replacement engine 25 hrs on it. Bogged down after hitting a wave. Pulled and tested carbs they were fine took a look at the reeds as you can see In the picture I lost 1 and the others look to be shredded not melted all are on the forward facing reeds both sides. Engine compression is now 110 110 90. 90 is on the cylinder that took the reed in. My only thoughts are crank is out of tolerance and clipped the reeds? Any chance the missing reed is causing compression to come in low? What are your thoughts on pieces of reed causing further damage?
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    Last edited by Doorgunner; 07-27-2014 at 07:19 PM.


  2. #2

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    Did you replace the reeds when you installed the engine? Always good to have new reeds with a fresh motor. Those reeds are fiberglass, and don't USUALLY.....key word USUALLY do damage when they break. They usually go through the motor and out the exhaust port. If you still have the motor in the hull, I would suggest installing a new set of reeds....I currently am running SBT reeds, and have had no problem, and crank and run the engine for a little while.....lightly throttling it, and see if you can get that Reed to come out. It's not metal so it's not gonna hurt the motor. Check compression and see if it comes up. Thinking about it a little more.....I think a missing Reed would cause compression to be a little low. Can't build enough crankcase pressure to properly supply air/fuel charge to cylinder. Either way, you have lost nothing by installing new ones and testing. And, if the crank were out of tolerances, it would vibrate and hit the reed backing plate, not the reed. Hope this helps. Good luck and keep them fingers crossed!

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  4. #3
    Thank for reply. Fresh set of SBT reeds during install. Already pulled the motor out. Interesting that all the damage is on the front side of of each red set. If not crank must be some kind of turbulence in the air flow to make them flutter? Going to give them a call tomorrow good thing I got two year warranty.

  5. #4

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    "...good thing I got two year warranty."

    But you opened up the motor.
    Curious to hear what they say.

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  7. #5
    Spoke and sent pictures to SBT they didnt offer much as far as a explanation goes. They Floated the idea of debris in the crank. damage looks to consistent for that. im going to remove the reeds from the cage and see if the damage sections line up with the crank.

  8. #6
    sjorge3442's Avatar
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    Those reeds look melted, not broken. Maybe a super lean condition was present? Maybe a crank case leak somewhere, causing air to be sucked in somewhere.

  9. #7
    Thanks for replies. Now way it's the crank. Looks like the reed that broke off was hit by something. Carb is not missing any screws. Which means I must be more careful with keeping my work areas clean. Front cylinder burned upClick image for larger version. 

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  10. #8
    Happily Self-Employed WFO's Avatar
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    the crank can not hit the reeds

    most likely it was a backfire that took out the pedals

    possible causes of incorrect ignition timing could be a sheared flywheel key, or a broken flywheel, or twisted crank

    SBT cylinders are sleeved and most of the time the ports dont match up exactly, so it could have been a backfire from incorrect port timing (rare but possible)

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  12. #9
    Happily Self-Employed WFO's Avatar
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    you said "bogged down after hitting a wave"

    what exactly happened?

  13. #10
    Just that.Ski was running great big smile on the face then Landed a wave kinda hard. And she bogged right down immediately .Sounded ok at idle but give a little gas and felt like a cylinderwasn't-firing would only get up to about 6000rpm . Pulled and tested carbs they were fine. Seamed to sound fine on the hose at varying rpm's. But in the water it would bog down when you gave it gas. Checked compression 110,110,90

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