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  1. M

    2023 Yamaha 9.9 high thrust compression reading

    Two last pictures. It almost looks as though there is a low area in the cylinder walls. Almost as though the boring of the liner didn't make it as far as the casting. Notice the amount of carbon still there even after their supposed cleaning. Either that or the rings could be stuck in in that...
  2. M

    2023 Yamaha 9.9 high thrust compression reading

    There was scoring on both but the one with that picture was worse. The black plug was the top cyl. They have agreed to pull it apart as too much looks wrong. Also even with their carbon deep clean, the pistons and head are still caked with carbon, With that scoring and the condition of the...
  3. M

    2023 Yamaha 9.9 high thrust compression reading

    This is a shot of the cylinder when first taking in, you can somewhat see the carbon on the pistons and the scoring on the cyl walls, also the back of the valves were totally caked with carbon.
  4. M

    2023 Yamaha 9.9 high thrust compression reading

    Just got off the phone with them. They were supposed to call back 1st thing this morning but didn't so I texted their shop manager. It's supposed to snow here Thursday so told him I was dropping the boat off tomorrow so at least the boat was there. Also said I would like a new engine or at the...
  5. M

    2023 Yamaha 9.9 high thrust compression reading

    That was my thinking with both cyl low, but if that were the case, wouldn't water in the cylinder have cleaned the carbon off? Also my borescope attachment shows the valve edges as bad. Already called Yamaha, got nowhere, they just said go back to dealer for another carbon clean. Also they said...
  6. M

    2023 Yamaha 9.9 high thrust compression reading

    Thanks Boscoe, that's what I was looking for. I knew 50 was way too low. They were trying to get out of it by saying even though readings were low, they were even, so nothing was wrong. They totally wanted to ignore the fact that after cleaning that with 1/2 hr running time, the top plug was...
  7. M

    2023 Yamaha 9.9 high thrust compression reading

    Wondering if anyone has a shop manual to know what compression reading I should be getting on a almost new Yamaha 9.9 high thrust. I kept having to turn the idle screw up every couple weeks last summer and finally ran out of adjustment at the end of year. I was taking it to the dealer for some...
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