[robc68fb]

Hi,

I have a Murray riding mower with a 12.5 B&S vertical shaft motor. I recently did a dumb thing & not checked the oil for a while. Well, Here's what happened. The day the oil was low I had mowed some of the lawn & all of the sudden the engine slowed down really fast. So, I dis-engaged te blades & then the engine stopped. Fearing the worst, I let it cool & later figured out my mistake. I was able to rotate flywheel, so I decided to take the head off & see if I could see any damage. None was evident, so I smeared a little fresh oil on the cylinder wall & put the head back on. It fired right up & I mowed the rest of he lawn.

"Home free I thought". A week went by & I decided to mow the lawn, it started right up & lasted about 30 sec before the conectiong rod exploded.

So, I got a new connecting rod & gasket set, & tore the motor apart & put it back together. After I put it back together, it started right up & I let it run on 1/2 throttle for like 30-40 seconds & shut it down. I seemed to run good, but it seemed louder than normal. Anyway, I tried to start it again a minute later & it would not start. It fires & runs very weakly for a second or two, but nothing more than that. I thought maybe I had the gotten the rings lined up possibly, I took it apart again, & found that the top ring was just about in line with the oil rings on the bottom, but the ring in the middle was not in line with either set.

The only thing I could think it could be was a piston ring issue. So, I bought a set from Napa that .010 over. They said that carry .010 & .020 over & that is it. Should these work? Or, do I need to bore out the cylinder for those? Or, should I get the STD ones?

Any Thoughts/comments/suggestions/advice would be more than welcome! Thanks!

[thebriggsdude]

You'd have to bore the engine .10 over, to put .10 over rings in it and a new piston to fit the new bore size.