jets for 1974 johnson 70hp

[scottgsa]

I was just given a boat my dad had for several years. It's a norris craft and came from Norris Lake Tennessee at a fairly low elevation. We took it out often several years ago and it ran nicely. It's got a Johnson 70hp seahorse outboard. We live in Colorado (about 5600ft altitude) and the boat idles beautifuly but when you throttle up it bogs down and looses power and sputters. Wondering if it needs to be rejetted for high altitude? Could it be a timing issue? Any info would be greatly appreciated. New to boats!

 

[sgtmaj83]

I would suspect the carbs need a thorough cleaning.

 

[scottgsa]

They cleaned carbs and put gaskets in about 6 months ago but it hasn't been run since...I'll start with that anyhow!