OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines B&S 12.5 HP I/C Quiet, exhaust valve retainer.

Looking through the factory parts list, it seems that there was a change in piston design, during this model's production run.

Both 'Standard' and 'Standard, Chrome' ring sets were available for the earlier type, used 'Before Code Date 01060700'.
But the Chrome ring set wasn't offered for the later piston, used after that date.

So it would appear that the supplier is correct in this case, if they are supplying the late type piston.
If the original piston was re-used, chrome rings could be used too.

The chrome ring sets Briggs supplied were somewhat a 'field expedient' really. Used to get a bit more use, without excessive oil consumption, from a tired engine that wasn't worth the cost of reboring/honing out and oversize parts. They do work in the aluminium bore engines too, and were available for most of them.

But with labour costs these days, these rings wouldn't be in much demand, in the US at least. Not much more money to fit a new engine over there, compared to an overhaul.

From the Briggs #270962 Repair Manual:

Thanks Gadge, in those days at least, Briggs' engineers knew what they were doing, so it appears that the chrome plated rings can be used in aluminium bores. Did the chrome plated ring sets come with chrome plated steel rail oil rings? I don't know how the ring pressure from those steel rail rings with expander, compares with the pressure from cast iron one piece oil rings. If the pressure is the same, it should work.

I will definitely keep the chrome rings in mind, as an option down the track.
They just didn't work out for me this time.
It is a great tip for getting a bit more from an old engine.

I have also learnt to now look at the parts lists more closely.

When the bits get here I will continue this thread.

Yep, they have the 3-piece oil rings, and as I recall it the rails were chrome plated.

It appears that the standard ringset oil ring type for this model is a two-piece cast iron, with the internal spring expander.

Yep, so long as the ring tension is appropriate to the design, both will function equally well.

Bits have arrived. Piston and rings are marked well.

This engine is pretty much back together, here are some progress shots.






Just have to make up a heat shield for the muffler, add oil, connect up a fuel tank, mount the engine for a bench test.

Hello, engine is finished and running well.



I turned the engine over with the spark plug out to bed the rings in a bit, prior to trying to start it.
It is a nice tight engine and the battery and starter motor wouldn't turn it over initially (battery is not the best either). I had to wind it back to get a run up at compression.

It eventually fired, again I forgot to check the governor arm, which was removed to replace the seal, it didn't over speed, just wouldn't idle.

With all parts cleaned, valves service, all new gaskets and seals, honed bore, new piston and rings, this engine now idles and runs smoothly at revs. Ready to go back into service.

Thinking back, I should have stopped using it when changing the plug, magneto and cleaning the carb didn't fix it.

This was my first large Briggs engine and I didn't find it too bad to work on.

To Grumpy, Gadge and Roebuck. Thanks much for you generous advice.

Here's another piece of advice, Mark: if it was tight after initial assembly, and didn't free up completely immediately after a very short no-load run, it is likely to need prolonged and careful running-in, or it may seize partly or completely. That ruins engines, so I suggest you avoid it. Did you check the ring gaps? If it is just the honing marks in the bore making it tight, a gentle run-in will save it, but if the ring gaps are too small, it's going to seize, the only question is when.