Safe Cruising RPM for F70LA

[Mark Sebright]

I recently bought my first boat and it came with a 2015 Yamaha F70LA 4 stroke engine. If I remember correctly the redline is 6300 RPM.

What I am wondering is what is the maximum safe cruising RPM for this engine?
It is broken in and the oil and filter have been changed. The boat planes out fast and it runs across the lake great at anywhere from 4200 to 5300 RPM's

I took it up to 5300 RPM for the first time the other day and it ran really nice across the lake.

My question is will it hurt the engine to cruise at that high of RPM?

 

[robert graham]

It won't hurt it to run it in the mid- 5000 RPM range, in fact I doubt it would hurt it to run near red line....but I've never been totally comfortable red-lining a motor for mile after mile. And best efficiency in miles per gallon is usually mid range around 3500 RPM's....Go to Yamaha Outboard Performance Bulletins for MPG, MPH, GPH, etc. at various RPM's for your specific motor/boat rig.....Good Luck!

 

[Mark Sebright]

Thank you for the response. I thought I was probably safe with it being 1000 RPM below redline but I am still new to outboards so I wanted to confirm.

I checked the performance bulletin for my boat and engine combination and it shows optimum overall efficiency at 4000 RPM and 33.5 MPH at 6300 RPM.

You loose two miles to the gallon for the extra speed at 6300 RPM but its still getting over 5 miles to the gallon so that's not bad.

 

[robert graham]

Yep, you'll establish your own "comfort zone" regarding cruise speeds/RPM's....I ran a copy of the performance bulletin for my rig and keep it on the console...just for information/fuel management...