Stihl 200 Piston SHATTERED

[MapleSyrupGivesMeStrength]

I have been rebuilding my MS200. I love this baby. Even it becomes a Frankenstein saw, where just about every single part has been swapped out, I want to keep it going. Most recently, I had replaced the cylinder and piston. They both came from the same seller. It was on Ebay. I have usually had good luck with OEM parts from sellers on Ebay. Well, after putting everything together, I fired it up. It sounded better than it has in a very long time, for about 15 seconds. The saw stopped, and I was not able to spin the flywheel anymore. After taking it apart again, this is what I found. The piston just crumbled. These parts looked great, and really looked like a match to the original piston and cylinder. Is this bad manufacturing? False advertising of parts that are not OEM? Did the piston rings spin after I compressed them to get them into the cylinder? I'm really shocked to see this and I wonder why this happened, and I am trying to figure this out before I  put the old piston back in. 

For background, I bought a new cylinder because the spark plug kept leaking during my pressure vac test. The threads were bad, so I redrilled the threads, and it kept leaking so I tapped out and got a new cylinder. A new piston came with the cylinder so I installed that just for the sake on consistency. No leakage during the last pressure vac test. 

[spudulike]

You put the piston in back to front, the arrow points towards the exhaust port, in your case, it is pointing upward towards the inlet port.

All parts are OEM but the ring ends have caught in the exhaust port and smashed the piston up.

A little knowledge is dangerous!!

[MapleSyrupGivesMeStrength]

14 minutes ago, spudulike said:

You put the piston in back to front, the arrow points towards the exhaust port, in your case, it is pointing upward towards the inlet port.

All parts are OEM but the ring ends have caught in the exhaust port and smashed the piston up.

A little knowledge is dangerous!!

Dammit. It felt a little too easy. I can no longer see the markings on the original piston. Is there another way to make sure that it is oriented properly.  

[spudulike]

The ring pins should run either side of the inlet port and NOT the exhaust port. You should be able to see the marking on the original piston if the crown is lightly cleaned of carbon.

Just look at what you did last time and do the opposite.