PAW liner alignment
 

I just took apart a gummed up PAW 19. I marked the back of the conrod and piston but did not mark the liner alignment. There is no obvious alignment with the circumferential porting and no register pin. I guess it only matters to get the wear pattern to match that of the piston or is there some secret code or mark to look for? I want the right alignment for reassembly....

AFAIK there is no code-secret or otherwise involved! You've only got a 1 in 3 chance of getting the alignment back the right way....could be worse-with some engines its 1 in 4 if you didn't bother to mark the alignment before disassembly. Shows the merits of using a pin to positively locate the liner. Personally-where PAWs are concerned I always make a mark at the top edge of the liner, at the front, before disassembling any further....I use a Dremel cutoff disc to just kiss the edge.....makes a neater job than a file.....and a scratch mark with a scriber point can be overlooked. If the liner comes out with the fins attached on initial disassembly I mark lower down with a felt marker till the components are separated then mark the top properly as before.
In theory.....at least you might be able to see some internal wear patterns-but a lot would depend on how much running the engine has done-and how much cleaning was done before reassembly.

ChrisM
'ffkiwi'

FWIW I devised a method to work out the right orientation that is perhaps better than guesswork. I tapped out the contrapiston and oiled up the bore and piston. Holding the liner in place by hand I twirled the crankshaft, feeling for how freely the piston rode up and down in the bore. One of the 3 orientations seemed freer than the other two so I took that to be the correct orientation.

'
That's probably about as good as you can do realistically-likely to be correct...and you wouldn't pick it up with the contra in place....

ChrisM
'ffkiwi'

If it turns out in due time that it wasn't the right choice just send it back to PAW for a rebore.