84 RZ350 Pro-X Expander Ring Yay or Nay?!

[Vincenthdfan]

Hello all,
I have a really nice, new to me 84 RZ350 yellow/black KR Edition with 7,000 miles on it. 

I am going through it top to bottom right now, new seals, gaskets, etc....

I just had it bored 1st over and am using cast Pro-X pistons (personal preference). 

I have been reading until my eyes are crossed regarding the expander ring that goes under the bottom ring on these Pro-X pistons.

I see some posts from way back saying there have been some broken off and destroying fresh top ends.  Has quality improved since then, is this still an issue?

I know the stock Yamaha cast pistons I just removed had them in place, albeit one was sort of stuck and gummy but no damage, just worn bores on both sides.

I really need to decide which direction to go here.  I spoke with Ed Toomey, he said run them, they're engineered for them so why not?  But if they still potentially break and ruin top ends thats a no go from me?

What's the general consensus out there now days?  I saw a reference "Chuck says toss them in the trash" but cant find that post...it must have been a long time ago, thus my question regarding are these still an issue, or has anything improved? 

Thanks in advance

[Gil Gallad]

if you believe ron at fahron - which i do - bin them i asked him the same question years ago and that was his answer 
cheers, gil

[Evans Ward]

Chuck Q./ Supertune also says bin them. I've got about 1000 miles on my RZ rebuild/ Pro-X without the expander rings with NO issues.

[Vincenthdfan]

Chuck Q./ Supertune also says bin them. I've got about 1000 miles on my RZ rebuild/ Pro-X without the expander rings with NO issues.

Have you noticed any additional piston rocking noise from them not being there?

[m in sc]

no. and they don't control that, the skirt does. I haven't run expansion rings in 30+ years.  bin em.

[Vincenthdfan]

no. and they don't control that, the skirt does. I haven't run expansion rings in 30+ years.  bin em.

Fair enough, that's what I needed to hear.  I wont use em if there's going to be no negative effects from their absence?

Any idea what the point of them is?

I know one of my pre-existing OEM pistons had the lower ring pretty well gooed up and stuck even with the expander in place behind it at 7,000 miles when I pulled it apart so if it's intent was to prevent sticking it didnt fix anything.