Piston rings, which way up?
 

Hi guys the Haynes manual I'm using states that the second piston ring is tapered and must be installed the correct way up, but the ring doesn't appear to be marked in any way and I can't see a taper with my eye. Any advice on how to tell which way up it goes?

Many thanks as always!

Use magnifying glass and spread apart ring-gap and look at ring-ends to see profile shape.

Tried even with a magnifying glass and I can't see the tapered edge... Am I being thick?
https://cimg2.ibsrv.net/gimg/cbrforu...c9c1dd4f19.jpg

Looks like it’s facing down in your photo. Flip it over and take another pic.

Yeah, taper’s usually more pronounced than that. Did someone sell you used rings?

These are, I believe, the original rings so they've done 50k miles 🤣

Sadly I can't find new ones for sale anywhere I've even asked in Japan to no avail.

I figured out which way up they go as they all have a dark line close to the edge at the bottom (luckily I hadn't taken cyl3&4 ones off yet)

I'm sure refitting them is far from ideal but it ran reasonably ok before I took it apart (got her to 136mph on the GPS and wasn't burning silly amounts of oil), only reason for taking it apart is headgasket as that went, and sadly had to slide block off to seperate head!

eBay’s usually good source for parts of old bikes.
https://www.ebay.com/p/2085978728

Well found!! Are these suitable for the PC23 do you know? I don't know what the differences are between the different f1 engines

The bit that goes between the bottom rings looks very different to what I have on that set
https://cimg0.ibsrv.net/gimg/cbrforu...29340aaa57.jpg

so i guess these are, infact, not the original rings! they look like the ones for a cbr600RR. sadly i've no idea if its been rebored so i wouldnt know what size to replace them with. i'll try measure it with a caliper and see if i can tell if its 67mm or any more than that.

Yes measure to be sure.

Also 3-layers of oil ring is complete package. Doesn’t matter if centre is different.