I have just purchased a J-40 which is equipped with a Beta 38. What is the minimum RPM at which I can run this engine for long periods of time without carboning-up the engine? Thanks for your advice.
Welcome to the forum. The newer Beta Marine / Kubota diesels which are EPA approved run much leaner than the older generation diesel engines and you should be just fine running at any engine speed over 1,000 RPM for long periods of time without issue. Just make sure that you use a good quality diesel engine spec oil (like Shell Rotella) and clean fuel and you will be fine.
