Cavitation

[Dvesky]

I'm experiencing severe cavitation at 5500 rpms + when throttle is increased in one engine. While testing, I ran the boat on one engine and could not go past 5500 rpms without the boat increasing in rpm with no increase in speed. Wear rings were just replaced so that's not the issue. Any suggestions on what to check next?


The prop will eventually catch up and the boat runs fine at top throttle 45mph+ with both engines running

1998 Sportster 1800

 

[nisjeep]

Sounds like carbon seals or bellows. Space the bellows towards the seal with a zip tie. The idea is to put more pressure on the carbon seal.
If the cavitation gets less then you've found your problem.
This is not a permanent solution.