Altitude attitude

[6tring]

1973 Johnson 9.5hp. On a recent fishing trip I had transported boat and motor from an altitude of 975' above sea level to 725'.
I found that I had to dial the mixture adjustment to rich to get a smooth idle.
I would have never thought that 250 ft in altitude would make a difference. The motor was present for 975' The motor ran fine otherwise. Just thought I would share the experience.

 

[racerone]

Agreed---250 feet makes no difference.----What about air temperature ?---Different fuel ?----Have you checked thermostat on this motor ?----I usually find them stuck open or missing.

 

[6tring]

Same fuel same temp and humidity. 1 year old thermostat.Pumping good water. I will get out on the lake here at the 975' soon and see if I have to adjust back. As long as the motor runs fine so be it.