2003 OX66 VMAX 200HP Compression Numbers?

[carp104]

Hey guys,

I am looking into purchasing an used boat with a 2003 Yahama Vmax OX66 200HP outboard on it. The owner had the compression checked and found it to be exactly 90psi on all six cylinders.

Is this normal for this motor or does this seem on the low end? The way I see it is that it's unlikely for all cylinders to be on the low end and have the exact same compression, so this must be near the motors true compression?

Can anyone tell me what the compression should be for this motor or where I could find out?

Thanks a bunch

[Stratos21XL]

If all of the cylinders are the same or really close to the same I'd say your good. What I would highly recommend is having a leakage or leak down test done on the motor. This will assure you the cylinders are in good shape.

[Reata210]

Sounds a bit low. Could have been the gauge as well. You should be between 112-115 up to 120 all within 10 percent.. I second the Leak Down.