I have a 2004 29 Fountain Fever with the single 500 EFI (blue motor) and the XR drive. I'm curious to know at what point (in engine hours) should I be concerned about engine servicing, other than routine. I have been told that these engines and drives need to be torn down and inspected/serviced for internal wear around the 300 hour mark. any help would be great, thanks.

I would say at least valve springs and a leakdown test at 300 hours. If they have been maintained and not run super hard you are probably fine with that.

Thanks for the info. Much appreciated.