Twin 99 Yamaha 200hp OX66's. Max rpm issue. Please help

[Windham14]

Hey guys I own a 99 Contender 28 with twin Yamaha 200hp Ox66's. The boat has been a one owner boat up until I bought it a few months ago, always garaged and maintained with an open checkbook. Motors have 700hrs on them and I think I have a max rpm issue. The motors run absolutely flawless. Never have given me one second of a problem. Idle and cruise speeds are perfect. I found what I think is a max rpm issue when testing props. No matter what prop I put on this boat the rpm's never go over 4800. As stated before the motors run perfect in every situation and never miss a beat, I just don't feel like 4800rpm is enough.
Last weekend I replaced the following and got the exact same result last night....

- VST filters - they looked perfect
- Spark plugs - looked good
- All low pressure pumps
- Pulled 02 sensors and had them professionally cleaned
- New Racor fuel/ water filters

What is throwing me is the motors run to the exact same rpm and do it at the exact same time. How could both motors be experiencing the exact same issue? IS there an issue at all? The reason I think there is is because there should be at least a few hundred rpm difference between the 19 and 21 pitch props, there isn't.
I know the manual says 4500-5500 is the correct max rpm but 4800 just doesn't seem right to me.

The only other thing I have noticed is I can still pump the primer bulbs with the motors running- they are not rock solid. Is this an issue? Doesn't change a thing when I do pump them. Thanks for any help or advise. Just want to make sure the motors are at their best.

 

[99yam40]

primer bulbs are on the suction side of pumps so they will not stay firm when the pumps are sucking on them.

Not much help on the RPM limitation.
Might find a Yamaha shop that has the correct test props for your motors to see if they can turn them up to proper RPM while not pushing the boat/load.
If they cannot then you know you have motor problems,
if they can then you have a boat or set up problem.
Have them check your Tachs also to make sure they read correctly

 

[Windham14]

Does it matter if the primer bulbs are mounted between the tank and Racor filters or between the motor and Racor? Mine are also mounted flat instead of vertically. Is this something that should be changed?

 

[robert graham]

When running at wide open throttle 4800 RPM's are you then trimming the motors up to gain speed and RPM's?....

 

[Windham14]

These Contender hulls don't allow too much trim before the props blow out but yes I trim them as much as I can. This actually might be part of the problem, you can't trim the motors to gain rpm's