High Elevation Outboard Operation

[Timtactical]

Gents....and lady.

I am going to be heading up to Colorado in the mountains with an elevation of approx. 8955 ft above sea level. I have a 1983 Evinrude 9.9 that has been converted to 15 hp, I run it all the time on Kansas lakes with decent performance.

Now with my question....
Can I adjust the carburetor to run at such a high elevation or do I have to re-jet the carb. I have no intentions of changing jets or props for this weekend trip.

Thank you,
Have a satisfactory day.

 

[Timtactical]

There are from the last trip.

 

[PATRIOT]

Been there, done that. Tried it with my 15HP Nissan on the largest reservoir in Colorado . . . Blue Mesa west of Gunnison and it's at 7519' . . . I usually run at just 740' elevation.
Re-jetting is the only fix . . . if not, don't bother trying to get up on plane.

 

[PATRIOT]

Came across a pic of my 15HP Nissan at WOT in the Blue Mesa Reservoir . . . as you can see, it barely throws up a wake and never gets on plane at 7500' but moves along at 22mph at my usual 740' elevation.

 

[Timtactical]

I wonder if I am at an advantage with my 9.9 being converted to 15. The carb is larger which will allow more air, I will obviously have to adjust my fuel to match.

 

[kofkorn]

I would think that the only motors that have an advantage would be the older motors that have the Lean/Rich adjustments for high and low speeds. Anything with fixed jets would need to have the jets replaced.

 

[PATRIOT]

Timtactical » Today, 09:29[/url]"]I wonder if I am at an advantage with my 9.9 being converted to 15. The carb is larger which will allow more air, I will obviously have to adjust my fuel to match.

Except . . . in the case of my Nissan, the 9.9, 12 and 15HP all have the same displacement.
Judging from the looks of my wake, it appears there is plenty of exhaust "volumn" just not enough fuel.
Anyway, I'm shopping for a new EFI motor for my new hull, one that has a MAP sensor so I don't have to be concerned about operating elevations.

 

[PATRIOT]

Located a pic of my Nissan 15HP at WOT and 22mph in my normal lake at 740' elevation.
Quite a difference from the WOT at 7500'.