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  1. C

    Yamaha Harmonics problem

    Just did a rebuild on a '90 Yamaha ProV 150, replacing 2 pistons. Engine appeared to have failed from carbon buildup at rings (Pennzoil). Engine runs beautifully, but sings loudly from 37-3900 rpm's only, at all other speeds it is quiet. I feel if it were a bearing it would get louder with...
  2. C

    Yamaha Harmonics problem

    I just did a rebuild on a '90 Yamaha ProV 150, putting in two new pistons. Engine failure appeared to be from carbon buildup at the rings (Pennzoil if you're wondering). It runs beautifully, but sings loudly from 37-3900 rpms. It is quiet everywhere else. I feel if it were a bearing, it...
  3. C

    Yamaha Harmonics problem

    I just did a rebuild on a '90 Yamaha ProV 150, putting in two new pistons. Engine failure appeared to be from carbon buildup at the rings (Pennzoil if you're wondering). It runs beautifully, but sings loudly from 37-3900 rpms. It is quiet everywhere else. I feel if it were a bearing, it...
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