Anyone heard of these pistons or use one in there bike? NOS MC pistons? He said they take the stock Yamaha rings. 





 

Yes,  they are a good piston . . . BUT . . .  You must use MC brand rings !!
The OEM Yamaha pistons use the "Keystone" style of rings . . . The MC piston uses a "straight" cut style of ring

The Yamaha Keystone rings will fit into a MC piston ring land/groove, but not visa-versa . . . MC rings will not fit into a Yamaha brand piston
Just because the Yamaha rings will fit into that MC piston, does not make them correct.

In fact, I remember a fellow that destroyed his CT3 top end by trying to run the stock Yamaha Keystone rings in his MC piston.

Excellent, good to know. I knew Yamaha is Keystone, MC doesn't really say.  However i do see listings for MC keystone rings and std MC rings. Wonder if they made both styles or these E-bay listers just plain don't know what they have like a lot of times! 

 

Buy at your own risk! . . . most sellers probably don't have a clue, and couldn't tell between the two types ... even if they held them in their hand
I recon many sellers just use the word Keystone in their title to connect with more searchers ... then ... others cue off these mislabeled titles (when listing) cause they don't know any better.  If MC produced a Keystone ring combo for the CT1 model, I don't know about it !  

 I just checked 16 MC pistons sets that I have here in my stock, and all AT1, CT1, DT1 sets had straight rings
The only Keystone tapered ring I saw in my batch of MC pistons, was a DT2/3 top (dykes) ring . . . the bottom ring was straight.

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I agree most these e-bay sellers don't even know what they have or what it actually fits. I go by what i know and ask a lot of questions to the seller.

 I decided to go with a genuine Yamaha piston and ring set.  Now are all genuine Yamaha CT1 pistons and rings the same style of ring? std 1st 2nd,3rd and 4th over? 

Just curious if you've checked with Enduronut on a piston and ring kit?  He has a pretty good stock and I've always found his prices fair.  Especially since you know you'll be getting a matched set. 

No, I just assumed anybody who see's this thread would know I am looking to buy a piston and ring set and would message me if they wanted to sell some of there old stock to me? I could be wrong though.

I bought a Yamaha piston: 251-11636-00-00 and ring set : 251-11601-20-00 on e-bay tonight. Had to make a counter offer twice to get them at a decent price. Once i receive them it's off to Bill Bune machine shop for the 2nd oversize bore job. In the mean time i am going to rebuild the lower end and get it back in the bike.

Another parts outfit I see.. nospartsnow.. They have a collection pistons..
Sneezles61