On 15 May 2006 05:52:18 -0700, "Jens_Erik"
wrote:
I just bought a used Bayliner Trophy 23 foot and the engine is OMC 5.7
1989 (model 574 APRMED), i believe it has 250 HP. The prop is 15'' x
17''. But the max rpm I get is 3400. Is that the maximum rpm on this
type OMC engine? I should think it lacks at least 1000 more rpm. I
believe the engine should be able to get at least 4400 rpm at WOT. The
max speed i currently get is just 24 knots. The engine seems fine and
I just replaced the spark plugs. Anyone has ideas of what could be
wrong?
================================

It is difficult to say what the problem is but something is definitely
wrong. I have the same engine in a boat of about the same size and
weight and it tops out at around 4400 RPM and 31 knots, also using a
15 x 17 prop.

Have a good mechanic check out the engine. It could be anything from
poor compression, ignition problems or the carburetor, but it is not
developing full power.