Cavitation/speed issues

[Hat929]

Hi,

My AR230 2006 is reaching 42.5mph and I wonder what to do about it?

The engines reaching ~10500rpm and they seems to work fine, but I can see that port engine rpm gauge is jumping to almost 11000rpm when I have full throttle, cavitation? I can also see that the coolingwater from that engine isnt that strong compare to the other.
It seems that the impeller and seals are tight but I cant spinn it freely 360, with a bit pressure it spinns 360.

I have always wondered what kind of impeller I have (they where new when I bougth the boat), can it be a reason why it has never gone over 44mph?

I`ve attach a couple of pictures, do anyone see anything strange or have any idea what the next step is?

 

[Cobra Jet Steering LLC]

It looks like they installed new impellers and nylon liners the clearance looks ok speed is determined by several things, not just the pump.

 

[Hat929]

Ok, understood. But the problem would be somewhere in the jet unit?

The hull itself has no shells or algiers, the motor revs/spinns as it should. Any idea where I should be looking?
(I have owned the boat for 5 years and driven it about 30 hours, it has been the same since I bought it).

 

[Cobra Jet Steering LLC]

First thing that comes to my mind is air cleaner and fuel 30 hours in 5 years wiring connections, ground wires , plugs, plug coils compression stuck ring ,just too many things to hazard a guess but if that is all you use it and it goes 40 I would say use it and see if it gets better try one thing at a time until you find the issue

 

[Hat929]

Thanks for all ideas!
The motors has new sparkplugs, oil and airfilter since last year and new cleanoutplugs this year.
When I plug in the boat to the computer it doesnt have any warnings in the computer.

Should I try to buy new original impellers?

 

[Neutron]

That intake tunnel and clean out port doesn't look too good at all. That all can contribute to cavitation

 

[Hat929]

Yes the tunnel looks rough. Took a new picture with the cleanout plugs inserted.

Smooth it out with new gelcoat?