Rebuild Advice - Piston Pics - '86 Blackmax

hsdtech

Seaman
Joined
Mar 20, 2010
Messages
60
I finally tore down my '86 Blackmax to repair a cylinder w/low compression. The cylinder wall doesn't seem too bad, we're hoping to just hone it. This cylinder/piston is oversize, .015. The bottom ring is welded to the piston on one side. See pics. I'm thinking it overheated because of a plugged jet in the carb causing to lean out??? I bought the motor this way, knowing about the bad cylinder.
Maybe someone can tell from the pics what may have caused the problem. I'm planning on installing new rings on the other pistons, and installing a new piston/rings for the bad cylinder. Any advice will be appreciated.


merc piston 2.jpgmerc piston 3.jpgmerc piston 4.jpgmerc piston.jpg
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,616
Re: Rebuild Advice - Piston Pics - '86 Blackmax

You aint going to hone that cylinder and stay in spec's!!!!
 

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
17,926
Re: Rebuild Advice - Piston Pics - '86 Blackmax

What's the cylinder looking like?
That much damage on the piston.
The cylinders gotta have a groove or 2.
Clean it up and do the fingernail test.Pics??
If it can be felt by your fingernail it's gotta be bored.
Otherwise your just throwing away $$
Profile,location? You might be close to someone who can help.
 

hsdtech

Seaman
Joined
Mar 20, 2010
Messages
60
Re: Rebuild Advice - Piston Pics - '86 Blackmax

We honed that cylinder this evening and it is real smooth. It was more like alum transfer, not gouging on the wall. I'm getting a gauge tomorrow to measure it.
Here is a pic of the wall before honing.

photo33.jpg
 

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Rebuild Advice - Piston Pics - '86 Blackmax

You aint going to hone that cylinder and stay in spec's!!!!
Aint that the dang truth!!!

Did you clean that aluminum off the wall with muriatic acid before you honed it and did you use a real hone or one of those 3 stone expanding hones from Kragen/Oriely or such. I made that mistake once thinking it was just a dumb outboard motor.. Cost me a new 2 .0 fat block.
 
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