Got Flakes?

Early 2017 Update
It was a matter of time before the cylinders came off for inspection, and a persistent minor leak on the right was the reason this moment finally came.  I had re-torqued the head a few times already with no change, so after a little procrastination I got some new gaskets on order and got to work.

At first glance I thought all looked OK, until I noticed some scoring on the back side of the piston.  Then it was clear that one of the rings was ground into the groove near the exhaust side and the piston was scored.  A check of the corresponding cylinder bore location revealed an unsettling mark.  Crud, the chrome had flaked off in an area about the size of a 'Tic Tac'.  This cylinder is toast.  And a little scary at how close it might have been to failure, had I not checked.

Options ranged from sourcing used jugs, to NOS cylinders, to new Gilardoni cylinders.  And with or without pistons? Rings? Since an eBay search showed several reasonable used items, I decided to go the cheapest route (my usual!) and buy used. Including the pistons, which is good, as the scoring on my right piston has gone a little far for comfort.  I hope the photos and descriptions live up to the condition required to use them.  More when they arrive and the installation is done.

Follow-up: the used cylinder arrived, with chrome bores in very good condition.  And, the piston with which it is matched is in good shape, and the rings are free from obvious wear and move freely in their grooves.  Wrist pin also looks great; that was popped into the freezer for later installation.

Both needed a lot of cleaning, however; mud wasp nests and corrosion from the cylinder and carbon from the piston head.  My soda blaster was put to use as well, helping to strip decades of build-up; a water bath then neutralized the soda and all was dried.  Following the thorough scrub and cleaning (and aluminum paint on cylinder fins), it was time to install the piston, gaskets and put the head on.  I'd never held the 'beating heart' of a motor in my hands before, so was a little nervous about putting this all back together.  I further did not expect the wrist pin (a press fit) to be so snug.  A tool had to be made to press the old one out and the new one in (and installing it fresh out of the freezer overnight helped as well).  Below photos show the tool in action pressing the old one out, and then the parts of the tool.  Next time I will use a more robust bit of PVC tubing, but this worked well and I got the new piston installed without too much effort.

The head bolts had to be torqued properly before the valve clearance adjustments could be made.  While cold, the head was bolted down in a star pattern until very snug, but just under full torque.  At roughly 24 hours, the head was torqued to 34 pd/ft.  Then again, roughly 24 hours later the head was re-torqued to the same 34 pound feet.  Valve clearances were then both set at 0.006" (slightly tighter than Guzzi spec, I know).  Other note, both were at first measuring tight from prior setting, as evidence that the new gaskets are (obviously) not quite as compressed as the old ones were.  A day later I took the 850T out for a ride; it started quickly as usual and settled into an idle.  It rides at least as well/normally as before; revving easily no smoking or oil leaks.  Hooray!!

wrist pin pressed through the rod, and cylinder about to be dropped down onto base gasket