Hi Paul,
I may be a bit late to the party, but I just installed the pistons with new rings on my 3C. I have only
one ring compressor (new item and quite tall) so I ruled out trying to fit pistons into their bores after installing
them on their rods. I installed each piston with new rings from the top of the bores one at a time. I used
plenty of oil and tightened up the ring compressor. I did a few very light taps with a piece of wood and the pistons
dropped right in.
I also had all the case/barrel studs removed, so I installed two shorter ones on the upper edge as a guide.
I positioned the barrels on the studs and used a wooden spacer to hold them off the engine cases. Oh, I did
install a new base gasket beforehand. I practiced with few wood spacers beforehand to get the barrels as low as I could
and still access the piston pins. I also had installed the pins and the inner circlip for each piston before installation
into their bores. On the center piston I did not install the circlip toward the cam chain, just so I had more room.
The only tricky part was installing the remaining circlips, but once I did the first, the last two went
easier. Just make sure you cover any holes to the crankcase with rags when doing this operation.
It appears most contributors to the forum install the pistons the more traditional way, but I found
this method relatively easy and straight forward. Just take your time when turning over the crankshaft
to position the con rods so you do not expose any rings on the piston you just connected. I did the
inner first and the outers last. I did have to drop the barrel another an inch when I did the outers.
Good luck....
Keith