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Thread: tri moto teardown. Is this a aftermarket race piston or somthing

  1. #1
    Join Date
    Jul 2009
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    tri moto teardown. Is this a aftermarket race piston or somthing

    I tore down the 175 engine a few minutes ago. It has a wierd piston in it that doesnt use a circlip, it has some wound piece of metal that pops in the piston and there isnt a cut away out of the piston to take them out. Is this stock or does it have somthing maybe a old aftermarket piston kit? BTW the crank looks like brand new and it looks like it might have some porting on the jug which is bored .0020?? I ordered new circlips from dennis kirk and these are NOT what this engine has in it.....

  2. #2
    Join Date
    Feb 2006
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    EC
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    1,607
    I just looked at my Yt motor w/ the cylinder removed, & I'm seeing the same thing. I'm also curious.

  3. #3
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    Brian, why do you have your cylinder off? I think those are aftermarket pistons, but can't remember the name right off hand.
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  4. #4
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    Feb 2006
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    It's the cylinder from the 175 I got from Brapp, not the running one.

  5. #5
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    Nov 2008
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    Coon Rapids, MN
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    So Joel you got the engine apart then with out any problems I hope, that's weired about the piston though.
    1982 Yamaha YT125 tri-moto - Boyesen power reeds, YT175 front suspension, Headlight guard.
    1982 Yamaha YT175 tri-moto - Running but ugly
    1984 Yamaha YT 60 tri-zinger - Boyesen power reeds



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  6. #6
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    Jul 2009
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    yeah alex im going to switch out cranks since the 175 crank looks like new and is alot smoother. Does the yt175 exhaust use a gasket? My 175 jug uses like a piston ring that seals inside the exhaust........is that a dt, or it jug? Also there is a "half hole" in the exhaust port. Its like just below where the exhaust port opens......It looks factory and not a crack or chip...does yours have it? The best way i can describe it is it looks like a drillbit was put just below the port and half is in the jug and the other half would be where the exhaust port is......

  7. #7
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  8. #8
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  9. #9
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    Sounds like standard YT 175 jug, there should be two o-rings, one that's in the cylinder to seal the adapter that bolts to the cylinder, then the other one goes on the end of the adapter to seal inside the exhaust pipe, as for the rest of your post I'm having a hard time picturing what you are talking about. Sorry Alex
    1982 Yamaha YT125 tri-moto - Boyesen power reeds, YT175 front suspension, Headlight guard.
    1982 Yamaha YT175 tri-moto - Running but ugly
    1984 Yamaha YT 60 tri-zinger - Boyesen power reeds



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  10. #10
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    looking at the port it looks like a chip but it's hard to see as for the the exhaust i don't have that adapter on mine because I am using the stock YT 125 exhaust that just bolts to the cylinder, in till I can get my hands on a performance pipe, but If I was going to run the stock YT 175 exhaust I would have to get that adapter with the metal o-ring that you show in the third picture.
    1982 Yamaha YT125 tri-moto - Boyesen power reeds, YT175 front suspension, Headlight guard.
    1982 Yamaha YT175 tri-moto - Running but ugly
    1984 Yamaha YT 60 tri-zinger - Boyesen power reeds



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  11. #11
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    can you see the little half hole in the two pics of the jug? It looks factory as its dead center, anyone else have this?

  12. #12
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    Nov 2008
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    Coon Rapids, MN
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    956
    sorry I don't know what that half hole is for.
    1982 Yamaha YT125 tri-moto - Boyesen power reeds, YT175 front suspension, Headlight guard.
    1982 Yamaha YT175 tri-moto - Running but ugly
    1984 Yamaha YT 60 tri-zinger - Boyesen power reeds



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  13. #13
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    Aug 2009
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    i looked at mine i have a few lil dings here and there its just wear and tear man as long as they go in and dont putrude out u should be ok!

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