Has anyone actually tried a 428 O Ring chain on an 85 cc bike?
My son's YZ is eating up chain s like crazy. The muddy conditions are rough on these things, I know, but he only got about 4 rides
on the last RK chain I put on. I just ordered an O Ring for it
and gonna try it. At the rate of wear on standard, I'm not sure he will be able to finish a H/S this coming weekend.

Sorry,never tried using o-ring chains on the yz 80/85´s we had.I always had the impression that the RK chain was generally a good product,but then my son broke 2 chains that were fairly new,the plates broke,-not the split link!
Tried one more from the same dealer,one moto and it was completely stiff...
Maybe I was just unlucky,but I havent used RK chains since then...

Yes we have and they are OK. We use the DID ERT series gold. They are alot heavier about 30% thicker. These are mid way in price from basic RK/EK to O ring. We have 15 hours of Harescrambles amd GNCC racing and we will probably get 2-6 more hours out of it. We have gone through 4 rear tires in comparison....

good luck

Put it on and took it off. Way too much drag for the engine.

Where are you finding 428 O ring and ERT chains?  I was going to switch my sons YZ85 over to a 520 so that I could get the ERT chain.  Is that possible?  If so, what sprockets do you buy to fit.  I have not seen a 428 ERT chain for sale.

I apologize for the description....DID 428 NZ they used to be ER series but they changed the 420-428 to NZ last year.

Dennis Kirk, Competiton Direct, Parts Unlimited .

I can't find one either. I got the RK GB428MXZ as a replacement to the stock, has anyone had experience with? It is a heavier duty chain than the standard RK 428SO chains.

Actually the RK ones I tried are not good. Lasted for 3-6 hours and stretched like a stocker. Sorry.

Maybe I got a bad one. I have used RK520XSO and wow great chain.

My son has been using an RK 420 o ring for 1 year on his 80cc hare scramble KX. It may be noticeable drag but he holeshots or runs in the top compared to 85cc and 100cc bikes with some fast kids on them. We also have a steel rear sprocket. This bike is not set up for MX and by the time an hour race is over, there is way more mud than to worry about a little drag or excess weight. This bike has been ridden harshly ALOT. Of course my son is small but he is 13 and a decent rider. We would go to lighter stuff if we rode MX soley but right now durability is worth a couple of LBS and HP.

I got his 428 O Ring at "Chapparral Motorsports". I paid $66 total including
$17 for 3 dat shipping. Had to have it by the weekend. I put it on yesterday and it does have a little more drag, but maybe the pro's will outweigh the con's. He only rides HS and trails with the occasional MX just for fun, but does not compete MX. In the conditions we ride in, the standard chains was only lasting 3 to 4 rides and they were toasted and that's even after cheating and removing a link just to get by for the day. I also run steel sprockets on it.
He can take that little 85 anywhere I can take my 200 and sometimes better than I can. If it last any longer at all, it will be worth the money.

Oh yea, I forgot to mention that it's a DID 428v chain.

Found out yesterday when checking spokes, I've gotta replace his front rim.
He dented it in some rocks this past weekend. Must have been one of those times he run off and left me behind..........