1969 Yamaha R3 rings
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1969 Yamaha R3 rings

This is a discussion on 1969 Yamaha R3 rings within the Wanted forums, part of the Classifieds category; I have a 1969 Yamaha R3 and I'm trying to find the keystone rings in stock bore size. Any one have a set they want ...

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  1. #1
    Junior Member Geezergen's Avatar
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    1969 Yamaha R3 rings

    I have a 1969 Yamaha R3 and I'm trying to find the keystone rings in stock bore size. Any one have a set they want to sell. I'd really love to get this old bike back on the road.

  2. #2
    Senior Member Cyorg's Avatar
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    There are lots on eBay. If you decide to bore it out, I have new R3 pistons and rings .50 OS, but no standard bore R3, just TR2 pistons and rings.
    "Non urinat in ventum"

  3. #3
    Junior Member Geezergen's Avatar
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    Well, unfortunately, all the standard rings on ebay are the standard rings and not keystone type.

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  5. #4
    Junior Member Geezergen's Avatar
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    Well, unfortunately, all the standrd bore rings on ebay are the standard rings and not keystone type.

  6. #5
    Senior Member Cyorg's Avatar
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    Quote Originally Posted by Geezergen View Post
    Well, unfortunately, all the standrd bore rings on ebay are the standard rings and not keystone type.
    What pistons are you using?
    "Non urinat in ventum"

  7. #6
    Junior Member Geezergen's Avatar
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    I am using the stock pistons. Yamaha lists standard pistons and keystone pistons both for this bike and evidently my pistons are keystone because I have bought 2 sets of standard rings and they are too square section and also too wide for these pistons.

  8. #7
    Senior Member Cyorg's Avatar
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    Well live and learn. I wasn't aware the R3 used them. Mine are the normal rectangular ones. I haven't been inside any R3 engines other than the one I bought as a backup engine for the TR2 . The TR2 uses a single thin plated ring. You could call the fellow at Deves and see if he will make you some, but probably way cheaper to find some standard bore piston that use rectangular rings. You would likely have to send him a piston and maybe one of the old rings. He made me some rings at $50 USD per cylinder and they were straight forward. He may just tell you it's not worth it, but who knows.

    Shop High Performance Piston Rings Online - Deves.com
    "Non urinat in ventum"

  9. #8
    Senior Member XB33BSA's Avatar
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    Quote Originally Posted by Geezergen View Post
    I am using the stock pistons. Yamaha lists standard pistons and keystone pistons both for this bike and evidently my pistons are keystone because I have bought 2 sets of standard rings and they are too square section and also too wide for these pistons.
    does the design of the ring grooves allow them to be machined to fit the rectngular section rings ?
    it is a simple lathe turning operation to do so.
    you will notice almost all oem pistons have an inner land turned at the skirts interior bottom edge
    also most will have a small conical indent where a live center is used in the dome
    the piston is simply fixed to the lathe for turning by machining a piece of stock to facillitate the land at pistons bottom edge
    the live center from tailstock keeps the piston from launching out of the lathe into the machinists teeth.
    a simple driving dog arrangement is used to rotate piston against the cutting forces
    piston groove locating pins must be removed and if need be new locations for them can be used by simply reclocking them to the other side of the intake port
    the grooving tool should have very small radius honed into its corner profiles

  10. #9
    Senior Member Cyorg's Avatar
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    I believe they are, but.... the pins are located so only half of it is in the land. Removing them would be a colossal pain and machining out the part of it that is in the land (or using a tool post grinder) would be risky. Without access to a lathe, it would be much cheaper to replace the pistons with the rectangular ring type as they are readily available as are rings. I believe his are actually half keystone, so only one side of the land would require machining. If they are half keystone and the locating pin is on the opposite side of the taper, then you could sneak a cutting tool in there and turn that side of the land without fouling the pin.... but then you have to find some old fart with a lathe that is still willing to take on the odd project. Most I know are telling people to get lost, so they can focus on finishing their own stuff before they croak.
    Last edited by Cyorg; 09-15-2018 at 12:08 PM.
    "Non urinat in ventum"

  11. #10
    Junior Member Geezergen's Avatar
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    Yea I am looking for a set of standard bore pistons that use the standard rings. So far no joy on them either.

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