O-rings on outer crank bearings?

[RDnuTZ]

the aftermarket cranks I bought have O-rings on the outer L&R crank bearings. HPR has on both ends and Vito's only on 1 side. OEM cranks I have on hand have no outer O-rings and the official Yamaha website shows no O-rings there and no part# but does appear to show a groove for them but the pictures are not real clear to verify.

I'm trying to understand the purpose of these O-rings on outer bearings? 

[m in sc]

i run a few w the o rings, they are fine but as long as the c clip is there and there's a pip to locate the bearing its OK. the o ring is to keep the bearing from rotating

[RDnuTZ]

Thanks Mark. Yes, pip is there. Curious that OEM has no O-rings, Vito's has 1, HPR has 2. Yeah def don't want the bearing spinning. Ever tried a dab of adhesive on the non O-ring set up to keep from rotating or no need due to compression of case halves locking it in place?

[m in sc]

I haven't but Chuck q would use green loctite when the bearings w out the pips weren't available for a while. imho  i like the o ring better. bt you need an available groove for that so..