2010 AR210 motor is making a knocking sound

[Dormanjb]

My 2010 AR 210 Yamaha jet boat port side motor started making a knocking sound. The sound is only detected while idling and at low RPMs. At higher RPMs, it seems to run fine. Sometimes while idling, the RPMs are affected by the knocking, as indicated on the RPM gauge.
Last year I took it out and it went into limp mode and indicated it was overheating. I took it to a mechanic and they replaced the thermostats and it hasn’t gone to limp mode again that’s the only maintenance I performed on it since I owned it.
I have a video showing what I’m talking about

 

[tdonoughue]

First thing I would do is pull the pump on that side. Make sure there is nothing in the jet causing the noise. See the FAQ about how to do it. Start there because it is so easy to do... even if you think it is the engine itself.