Pull both spark plugs so it is easy to turn over
check to see if the piston in the cyl with no
compression moves. That would at least tell you
if you have a broken rod but if it is running
on one cyl do not run it any more till you figure
out why it is running on 1 cyl. If all you need
so far is a rod and gasket kit you are lucky but
that will not last long if you run it on 1 cyl.

I would remove the valve cover and see if maybe you are lucky and it has a bent push rod, broken rocker arm, stuck valve, loose valve seat.

Sticking long screw driver, dowel rod, etc. in spark plug hole will tell you IF piston is moving when you turn the engine.

Sorry, can't tell you about the connecting rods, maybe Mownie will chime in here.

Walt Conner

My assumption on why Briggs went with a "crank and rods assy" instead of the traditional itemized replacement parts is so Briggs could take a cheaper path in machining the cranks and rods.
Essentially the new cheap method is kind of like each crank and rod set is a "custom fitted assembly" where the dimensions of the components and oil clearances etc. are machined to fit only the mating part in the specific assembly.
This method gives Briggs a way to utilize crankshafts and rods that might have been culled out under the old method.

Parts made for the old method must be machined to exact tolerances and be identical so they can fit cranks made today and 3 years ago.
With the new method, the 2 rods and crank are machined to fit each other only and so all 3 pieces must stay together as a "matched set".
I don't know how many cranks and rods Briggs was having to reject with the old method but I bet they don't have to trash as many in the new method.

"Essentially the new cheap method is kind of like each crank and rod set is a "custom fitted assembly" where the dimensions of the components and oil clearances etc. are machined to fit only the mating part in the specific assembly"

Hmm, in other words, the way automobile engines were made before Henry Ford Standardized parts which made them much cheaper and faster to do. Prior to that, each rod, each piston, each set of rings were hand fitted to that particular cylinder bore and rod journal.

I guess most of you can't remember that far back.

Walt Conner

Some of the "logic" being used by OEMs in the present time almost seems illogical to me.

When the "standardized parts" concept replaced the "custom fit parts" method, it became much faster and cheaper because assembly personnel with little or no mechanical skills/training could be utilized instead of master machinists.

In the present time, robotic equipment is able to do many of the operations that once required a human eye and hands.

As OEMs try to engineer and tweak every step in every procedure to consume the least amount of energy and produce the smallest amount of left-over or wasted material in one part of the production sequence, they risk having more "rejects" or unsuitable parts.

Applying the "custom fit parts" concept can allow parts that might otherwise be rejected because they could not be machined to a specific standard...........to still be used (instead of being tossed out).

The manufacturing of a crankshaft is probably the most expensive process an engine OEM must deal with.
The desire is to be able to get as many castings or forgings of crankshafts as possible from the least amount of raw metal.
In a given "run" of casting or forging, you can expect to have some examples that would be rejected because the rod journals did not "clean up" at the standard diameter.
By utilizing the custom fit method, the crank journal can be further machined to a smaller diameter and the connecting rod for that journal can be undersized.
Using robotic equipment for the process makes this work with a degree of certainty that could otherwise be attained only by a highly skilled/payed machinist.
But this method produces assemblies which must be kept intact as a matched set in order for the concept to be practical for the OEM.

I was recently "educated" on the aim for increased application of robotics in industry when I ordered some instrument panel "lamp assemblies" (light bulbs in sockets) for our forklifts where I work.
These lamps are proprietary to the OEM and the OEM parts division is our source for them.
The bulbs are about the size of a "tic-tac" candy mint, in other words, small.
Down through the years, I have always ordered the bulbs as a "10 pack" and the size of that 10 pack was close to the dimensions of a deck of cards.
Well, the last batch of bulbs I ordered (as a 10 pack) arrived as 10 individual cardboard boxes that measured 1.25" X 1.25" X 2.5".
Each box held 1 bulb, all wrapped up in a roll of cushioning foam.
I called the parts dept at the dealer and asked what the heck was up with the new style packaging.
His response was that the OEM parts division had a new warehouse and distribution center..........and all the stocking and "picking" of parts is done with robotic equipment and the carton is sized to fit the robot "fingers".
All this to eliminate a human worker.
And this is only the tip of the iceberg.