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1984 Johnson 60 twin

guido2

guido2

Regular Contributor
Hi, Guido here and just asking if any one knows why the .030 over pistons for this motor have a different skirt cut out than the original pistons. I noticed that the new pistons are the same skirt as a 1995 40h.p. that I also worked on. Of course the bores are the same, but is the newer, smaller cut out, an improvement for performance or longevity or both? Thanks, Guido
ps. I noticed that the newer motors had a bit heavier connecting rod too.....just about 25 grams....with different pin oiling holes, oriented from the side instead of from the top (seems good idea as rotation would aid in the oiling)
 
Hey anyone wanna try to answer this one? Maybe I should change the jetting too. ( 56d and 55d right now ) Final sized piston clearance to .0035. Motor will be running at about 1000' elevation. Where are the sharp techs out there? Help please! Thanks, Guido (Tim)
 
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