Setting Spark Plug Gap

[Mike4049]

I have a 1990s 4HP Johnson outboard. I am changing the plugs but don’t know what the gap setting should be. How do I find out? No manual came with the outboard. Thanks.

 

[Bayard Gross]

Try .030 inch

More likely than not, the spark plug gap on that motor should be .030 inch.This is based upon my 2 and 6 horsepower Evinrudes of the same vintage which both use .030 inch.