Why run these pistons? They are not suitable for racing. They are prone to failure, from several differant causes. The service life is short and if the coating is damaged...which is very easy to do...wil eventually gall itself to death in the cylinder. Now these pistons are not even close to cheap...why not spend just a few dollars more for a good quality aftermarket piston? You will enjoy a much longer service life...and a performance advantage too.
I agree with Will on this one....(SHHHHHHH, don't tell him)
Bought new, the Briggs piston IS expensive! They are not a "performance" part and not held to the same manufacturing tolerances of a performance part! We are putting much higher stress on the parts than they were designed for.
I don't think it is so much that some people got some "bad" ones as it is that some people like Paul got some "Good" ones!
Small engine mechanics - How many engines have you seen with "bad" pistons? rarely! For their intended purpose, they work great!
WIth all that said - If your cracking one side of the wrist pin holes - then one of 2 things is happening - one side is weaker, or you are not loading them evenly?
Is the bore square to the crank?
Is the bore round?
How much end gap on rings?