1991 Mariner 135 spark plugs

[reelnmn]

I'm primarily looking to increase my knowledge of my outboard motor. I read a few spark plug articles that stated you could read a plug and determine the characteristics of your motor. I.E. running lean, rich, etc. I've had a few issues the last time out with the motor being uncharacteristically difficult to start. The plugs were changed a year ago and I decided to pull them to take a look. There is quite a bit of build up on the plugs. Is this typical of an engine running too rich?

Also for a little background. The motor/boat was purchased in Virginia with elevation at 2000'. Now I operate the boat out west routinely with an elevation of 3-4000'. Thoughts?

Chris

 

[gbrowne9]

Re: 1991 Mariner 135 spark plugs

i think you need to rejet the carb,s for higher elavation but i don,t know the formula.the air is thinner the higher you go so your motor will be running rich.there must be a chart you can google.

 

[reelnmn]

Re: 1991 Mariner 135 spark plugs

The service manual I have recommends changing from a 0.064 main jet to a 0.062. Anyone know how much of a difference I can expect by this small change?