Spark plug pictures on a 3 cyl 90 hp

Sportsman558

Cadet
Joined
Mar 8, 2010
Messages
16
Starting from top cylinder to bottom (left to right) these are the spark plugs I ran at break in approx 3.5 hrs is this normal for top to be more black then bottom?? Thanks for the help
 

Attachments

  • IMG_0257.JPG
    IMG_0257.JPG
    66.1 KB · Views: 0

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Spark plug pictures on a 3 cyl 90 hp

Starting from top cylinder to bottom (left to right) these are the spark plugs I ran at break in approx 3.5 hrs is this normal for top to be more black then bottom?? Thanks for the help

What does break in refer to? Is this a new engine or did you just rebuild it?

In general, the rings on #1 will begin to plateau the cylinders and seal first. This is mainly due to heat. #3 will often run colder and wet at idle but will come around after about 10 hours or when your finally running at 50:1 mix.
 

Sportsman558

Cadet
Joined
Mar 8, 2010
Messages
16
Re: Spark plug pictures on a 3 cyl 90 hp

Shes a rebuild, break in refers to the 10 hours. So its normal for the top to be more fouled out then the bottom? Thanks for the help!
 
Top