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  1. #1

    Which pistons should I have 03 gp1300r

    I ordered pistons for my 1300, then I got reading thru the service manual and noticed that there's different pistons available. If I'm reading the manaul rite, the # on my cylinders is 12 so I would need pistons with the green mark on them. I think the ones I have coming are the red ones. What is the difference in these pistons? Thanks, Donald


  2. #2
    Chine Walker
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    For new cylinders with "12" on them, they would measure 84.012mm bore. Green pistons fit clylinders with a bore range of 84.011-84.015mm.
    Red group pistons fit cylinders of 84.000-84.005mm. Seems if you are recieving red group pistons, your piston to cylinder clearance will be too large.

    jp

  3. #3
    So what's the reason for yamaha having four different sized pistons?

  4. #4
    The rings are all the same rite?

  5. #5
    Hydrotherapy's Avatar
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    Quote Originally Posted by DONALDBUCHANAN View Post
    So what's the reason for yamaha having four different sized pistons?
    machining tolerances ..

  6. #6
    Dave Sharp dav_dman's Avatar
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    Quote Originally Posted by jpa1300 View Post
    For new cylinders with "12" on them, they would measure 84.012mm bore. Green pistons fit clylinders with a bore range of 84.011-84.015mm.
    Red group pistons fit cylinders of 84.000-84.005mm. Seems if you are recieving red group pistons, your piston to cylinder clearance will be too large.

    jp
    yami tolerances are way too tight for the demands we place on our engines, in my opinion.

    For pro-x , you need 4-5 thou clearance.. for wiesco, you need 7-8 thou or else you MUST do a 5 min warm up..forged pistons heat and expand more quickly than the surrounding cyl wall if you allow them to by high load demand too quickly. For oem yami , forget the matching..get the smallest size. For example, the 0.012mm difference above converts to a half thou clearance.....that's 5 TEN thousandths of an inch of clearance. Great for a bmw 4 stroke , but sucky for a high loaded , modified, open cooled two stroke.

    it's all a matter of opinion, of course.

    did you happen to blow #3 cyl? i have a friend who did..on an 03 gpr...and i read pistonwash post where it looks like flyboy just did that...
    and i know kerry had issues with 03 efi not keeping up.. but i think flyboy had the riva controller also..
    Last edited by dav_dman; 08-19-2007 at 09:30 AM.

  7. #7
    txgp1300r's Avatar
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    Quote Originally Posted by dav_dman View Post
    yami tolerances are way too tight for the demands we place on our engines, in my opinion.

    For pro-x , you need 4-5 thou clearance.. for wiesco, you need 7-8 thou or else you MUST do a 5 min warm up..forged pistons heat and expand more quickly than the surrounding cyl wall if you allow them to by high load demand too quickly. For oem yami , forget the matching..get the smallest size. For example, the 0.012mm difference above converts to a half thou clearance.....that's 5 TEN thousandths of an inch of clearance. Great for a bmw 4 stroke , but sucky for a high loaded , modified, open cooled two stroke.

    it's all a matter of opinion, of course.

    did you happen to blow #3 cyl? i have a friend who did..on an 03 gpr...and i read pistonwash post where it looks like flyboy just did that...
    and i know kerry had issues with 03 efi not keeping up.. but i think flyboy had the riva controller also..
    I agree with that

  8. #8
    I had an oil injection failure and took #2 rod bearing. Caught it before it did alot of damage. So what you're saying is I can actually use these pistons? I was looking thru the manual and I was thinking there wasn't much difference in them. That's one thing I've always hated about Yamaha, They seem to like complicating things. My son has a 1992 YZ125 sitting in the garage because he can't get a rod bearing for it. Go figure, Donald

  9. #9
    My last post I said rod bearing. I meant rod

  10. #10
    Duke's Avatar
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    Quote Originally Posted by DONALDBUCHANAN View Post
    The rings are all the same rite?
    YES.

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