OEM RD350 piston rings

[Still biking]

Can anybody tell me what the hexagonal flat wire is used for and where it is on the OEM piston? See the package of OEM piston rings. Its in the center of the package.  https://www.ebay.com/itm/Yamaha-Piston-Rings-R5-RD350/401759387022?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D56111%26meid%3D07b409c52fe2499c9ce4bd4f73f0004b%26pid%3D100675%26rk%3D5%26rkt%3D15%26sd%3D142876580228%26itm%3D401759387022&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3A01688cad-6f70-11e9-8e1a-74dbd18049c6%7Cparentrq%3A899294e616a0ac1cc237ffa9ffeeaf94%7Ciid%3A1

[SoCal250]

The thin wavy ring is a ring expander that goes under the bottom ring. Many engine builder these days throw those out and don't use them because they can break.

[Still biking]

I can believe that.  The oem std pistons that I have taken out of RDs did not come with them, I believe.  At least, I didn't see any.  I have one I will be opening up soon and will look for that little thing.  Thanks!

[m in sc]

they are supposed to have them if they are oem, so they probably werent installed. 

[quocle603]

while you're at it, re-hone your cylinder with fine stones.