Would higher altitude affect outboard from lower altitude?

[NOSLEEP]

Re: Would higher altitude affect outboard from lower altitude?

Mountianboy, I run my 85 evinrude 120 vro<br />every year at sea level for two to three weeks<br />in the ocean while on holidays. And the rest of<br />the year at 5600 ft above sea level at a <br />mountain lake in Alberta. I dont know alot about<br />marine mechanics.I can attest to the fact that I <br />have more power and can run 5miles phr faster at<br />sea level than at the high altitude. I know that<br />the jets are standard and have not been changed.<br />Over the 17 years I have operated this engine it<br />has caused no ill affect or any lean burning <br />problems with my motor.Its a little ruffer running<br />till warm at the high altitude but performs <br />flawlessly.

 

[mountainboy]

Re: Would higher altitude affect outboard from lower altitude?

Hey everyone, I messed around with the idle adjustments this weekend and got the ol' engine running quite well. I also changed spark plugs, filled the tank with a fresh mixture, changed lower unit fluid. I'm taking it out the next week to see how it performs on the water. I decided to take everyone's advice to leave the jets as is and work with what I have. Thanks alot and I'll talk to everyone later!! MB

 

[ChipWater]

I have a 2005 Johnson 15hp 4 stroke as well with only 10 hrs on motor. I actually have three. and they all fire up, need choke and a shot of starting fluid. I purchase from owner living at 1200 ft elevation moved it to 4800 ft and would like to use it at 6100 ft. But first: They all run just a tad rough/rich, at idle and low RPM, and seem like they just need a good cleaning out with some higher RPM. Plugs look and smell like a seriously fouled plug. Unfortunately I have no way of getting a rev capability in neutral on the remote throttle I have. I only have the high speed idle lever and that doesnt give you much RPM. So it stays rich. I am doing these runs with motor in a large plastic trash can. Spark plug called for is NGK - BKR6E
I was thinking of going with a BKR5E or 4E for a hotter spark. A few degrees of timing sounds good, but I need to get smarter. Once running good I can play with props. Think that 6K altitude is gonna drive a main jet change? My gut says yes, but? Thanks for the ear

MOD EDIT: This thread is 20 years old. Please be sure to review the forum rule about posting to old threads.