Circlip orientation and cylinder ID

[Scuffed98]

Doing a top end on my RD350. Kind of a noob question, but which way should I orient the piston circlip?
Also how can I ID my cylinders as OEM yamaha cylinders or Chinese ebay cylinders? It seems like someone has been in this motor before me.
 

[RDryan]

I can not answer to the piston circlip(s) position except to say pay attention to not accidently dropping it into the crank area when your properly seating them into the grooves they spring into of the piston.

Regarding identifying the cylinders I personally have Chinese cylinders and I can say they have these tell tale signs of not being original. For example they don't deburr the sides of the fins where they are cut to size and shiny. Also there is a cut mark, where a cutting tool just nipped the surface on the bottom of the reed area, it's not noticeable once installed. There is other differences for sure, maybe best to just take some good pics and add them to this thread. I'm sure somebody could tell you if they are original or not.

[m in sc]

the reproduction cyls have very 'sharp' defined casting corners on the '347' cc marking on the base. beyond that, its very hard to tell the difference TBH.

also, the clip, i always orientate the gap down if its a  full round hole, and if it has the 'pocket' i have one of the tails extend in the pocket. keeps it from rotating.

[Scuffed98]

Upon testing fitting my pistons I noticed that the piston seems to have a tighter fit at the bottom of the cylinders. Then, once it get closer to the ports the fit becomes looser. How concerned of this should I be or can I just run it as is? Right now I'm under the assumption that the only reason it's like that is because the looser part of the cylinder see's much more wear than the bottom. My cylinders are stock bore and I'm using a pair of 64mm ProX pistons. I measured my ring gap at around .009 inches