Hey Guys,
Just want to post my recent experience with the piston pins on my '78 XS650. I'm in the process of doing a top end rebuild and while soaking the pistons to remove carbon and varnish, I placed the pistons -- complete with pins and rings -- into a warm solution (about 150*) of heavy detergent. This was needed, because the compression rings were stuck in their corresponding grooves and I needed to free things up. The process cleaned the pistons of varnish and crud, but only softened the carbon build-up on the piston crowns; which was easily removed with a wire brush. The pins, however, turned a dark grey/black color around the journal where the connecting rod attaches (center section of the pins). The darkened area was covered with what appeared to be a black, slimy paste which I proceeded to wipe clean. BIG mistake!!! The goo came off alright, but exposed a rather roughened area along the center surfaces of the pins. I was totally taken aback by this, as I had no idea the pins were coated and that this coating would come off when immersed in a warm/hot bath, such as I had just subjected the two pins to, during my attempt to clean these parts. Prior to me immersing these parts into the cleaning solution, these pins looked OK, nice and shiny with no signs of excessive wear -- one reason why I thought they were polished or hard chromed. In conclusion, I made a mess of it and I will be shopping for new pins to replace the ones I destroyed. I hope this is of some benefit. DON'T SOAK THE PINS IN HOT DETERGENT!!!!!!
Cheers,
Norman C