1999 merc 125hp piston ring gap

bill j

Seaman Apprentice
Joined
Nov 27, 2007
Messages
47
I forgot to keep an eye on my 2stroke oil and damaged cyl# 3, It was lightly scored. I had a local machine shop hone all cylinders to which I kinda dont like the job they did. The book I have calls for .010-.018 ring gap. The new set of rings from marine pro has a gap around .020 ish when tried on all four cylinders. I only have the one set to try since the other 3 sets where wrong and are reordered. Will someone double check my ring gap specs to make sure my book is correct?
Cylinders 1,2 and 4 where undamaged and had the factory cross hatches. cyl 3 did as well except for one small spot that disappeared after the hone job. I am hoping the cylinders are not too large now. I will recheck the bore myself when I get to work. I am a ASE master tech. so I kinda thought i am up for the job. Lol
I just wish I kept an eye on the oil and or the alarm would have done its job!
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,930
Re: 1999 merc 125hp piston ring gap

Just mike your finished bore size as it should be 3.500, if its 3.504 or larger it time to bore it oversize.
 

bill j

Seaman Apprentice
Joined
Nov 27, 2007
Messages
47
Re: 1999 merc 125hp piston ring gap

I checked the bores, replaced #3 piston and all the rings. reassembled the power head and it runs great. I even replaced most all the bolts with stainless. now it looks great too.
 
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