Jetting for mountain use

[John McFarlane]

Hi all. How critical to engine power and lubrication is engine jetting please. I operate a 4.3m runabout powered by an 78 Evinrude 70hp 2 stroke at both sea level one week then at 4000 feet the next, and am mildly concerned/curious.

 

[LubeDude]

Re: Jetting for mountain use

The optimum thing would be to rejet, but because of the closeness of the intervals you are using the engine at these different altitudes, that just isnt an option. The best thing would be to just reprop when you go to different elevations. about a 2 degree smaller pitch at the higher elevation should help a lot. As to the lubrication issue, you will smoke a bit more at the higher elevation due to it running richer.