Thanks a million!!

Yamfan wrote: Keystone rings wont fit into the wrong piston groove.


A tapered top edge keystone ring certainly can be mistakenly installed on a piston with standard ring grooves.

I think anyone who has actually done that, needs their toolbox welding shut...........................lol

Yamfan wrote: I think anyone who has actually done that, needs their toolbox welding shut...........................lol

Wow. The fact is installing a keystone ring on a standard groove piston is a very easy thing to do...  most people wouldn't notice unless they very carefully checked the piston and made sure the rings they were supplied with were a correct match.  

(Which is probably why Yamaha marked their parts to identify the different designs.)

Yamfan wrote: I think anyone who has actually done that, needs their toolbox welding shut...........................lol

I've made dumber mistakes yet still enjoy riding and working on my machines. 


Frank; a lot of folks leave the expander rings out, as it's one more part to potentially fail. They are supposed to help with piston slap, yet even with them installed some noise at idle is the life of the 175cc machines for whatever reason. Good luck with your project regardless of using them or not!

Don't recal keystone having expanders. Do you have expanders. I've been wrong before--just can't remember when lol.

Yes the .25 over ring set came with 2 expanders I’m going to put them on first then the rings

Um, yes, put them on first.
But as Mark noted & i don't think i knew--expander for the top keystone groove [if you do have a keystone piston & rings] has a yellow paint mark & is narrower.
I guess you could unknowingly fit the yellow spot in the lower groove but then the other one i'm thinking won't bottom out in the keystone top groove.
Keystone tapered groove will be narrower at the base due to tapered ring being narrower on the inner edge.
Am i making sense--maybe not. Is there a K mark on the piston.

Thank you guys for your input I appreciate all of you !!