Low rpm's at wot 2005 90d yamaha

2005 xpress x17, 05 yamaha 90hp. Boat was new never in water when purchased in may of 2008 motor is a slightly used 2005 that was taken in on trade by the dealer. The issue's are I'm only seeing 4600 rpm's at around 40mph with 13.25 X 17 stainless 3-blade. Also there is oil in the air intake cover for the carbs, that drips inside the cowl appears to be coming from the carb's. The engine at least in my opinion is mounted to low propshaft is 7" below the the pad I'm waiting on a 6" jack plate to correct this. My concern is with the oil in the intake cover any ideas as to the cause of this???

Re: Low rpm's at wot 2005 90d yamaha

over propping can cause that oil puddle.
however we now have to find do you have a hull or engine issue, thats imperative.
using test wheel YB1620 it must be able to spin it at 5100-5300 RPM, if it cannot the engine is broke. if it can keep looking at hull/prop/mounting isues.
we dont mount general motors by propshaft heights, look at the ventalation plate, it should be level to 1" above the hull bottom.if your going to raise it any higher a water pressure guage is advised.
look at it this way a 13.25 Dia prop means from the propshaft centerline to the blade tip is 6 5/8's ".get the blade tip to close to the water line and it sucks air from the surface,ventilation.
while its on plane at or near WOT you want that plate about level with the water.
but at this point a run up on the test wheel is a must.

Re: Low rpm's at wot 2005 90d yamaha

rodbolt said:

over propping can cause that oil puddle.
however we now have to find do you have a hull or engine issue, thats imperative.
using test wheel YB1620 it must be able to spin it at 5100-5300 RPM, if it cannot the engine is broke. if it can keep looking at hull/prop/mounting isues.
we dont mount general motors by propshaft heights, look at the ventalation plate, it should be level to 1" above the hull bottom.if your going to raise it any higher a water pressure guage is advised.
look at it this way a 13.25 Dia prop means from the propshaft centerline to the blade tip is 6 5/8's ".get the blade tip to close to the water line and it sucks air from the surface,ventilation.
while its on plane at or near WOT you want that plate about level with the water.
but at this point a run up on the test wheel is a must.

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I have a dyno sheet for the motor the yb1620 wheel test passed. I've done some research and identical setups are running higher pitch 19 to 22 with jackplates this boat won't blowout at full trim I moved the engine up one hole no difference still can't over trim the engine. This engine was super low hours gentleman traded for the 4-stroke that was on this hull the dealer than put this motor on it. Any suggestions