[fanofjohnwayne]

My 1990 Yamaha 9.9 2 stroke keeps fouling plugs. What causes that?

 

[Brett]

http://www.dansmc.com/spark_plugs/spark_plugs_catalog.html

 

[noeettica]

try different oils ... and only run Real fresh gas ... Less than a week old ...

ask me how i Know LOL [smiley=fun_84.gif]

 

[Frank_Sebastian]

If you are using a "hotter" plug try going back to the standard one recommended for your engine

Best regards,
Frank_S