over revving

I am having a problem with one of the twin 787 engines. I have been testing it on the trailer. When I start the port engine it will idle at about 3000 rpm in neutral but bogs if I try to give it more while in neutral. When I put it in forward and give it a little gas it will over rev to over...

cavitation issue on a 2006 Speedster 200 i have twin 215s. when i give the boat gas my port engine revs higher than the starboard and has power loss. I have to give the port less fuel than the starboard to be able to plain with out over revving. Can someone tell me where to start? I haven't...