I picked up a 700 cheap that had a failed rod/crank. I rebuilt the engine with a used crank from the Polaris engine builder in Texas. I used oem crank bearings and seals. Numatic pistons and had new valves and seals put in the head. I found the oil relief valve stuck was stuck down to the bottom of the hole and had a very hard time getting it out. I honed the hole and replaced the valve with a small block chevy dowel and got it to slide nicely. New oem valve lifters and head bolts. I cleaned the cases thoroughly and sprayed brake clean through the oil passages with compressed air. Everything was meticulously assembled and torqued to spec.
Engine started up nicely and ran great for the first 100 miles. I dropped the oil and changed it for the break in period. 25 miles later it starts knocking. I pulled it out and the passenger side rod is starting to let go. I'm pretty sure its the same side as the original failed rod/crank. I deleted all my pics of the first tear down.
I'v rebuilt several engines in my time and this is the first one to fail on me. So I'm scratching my head over this one.
The engine builder who sold me the crank will sell me another one for $100. I paid $200 for the first one. I believe this was just its time to go. He says if it was bad it would of failed in the first few miles. But how can you know what the journals look like when you can't take it apart and inspect them before selling it?