Borring Clearance between piston and barrel

Discussion in 'The Workshop' started by dezze, Dec 8, 2007.

  1. dezze

    dezze Member

    Messages:
    148
    safe you lot
    I'm just in the prosess off reboring my barrel and fitting an oversize piston.
    I have cleaned the boremaster machine and me and the engineer at work where about to start boring out the barrel. When he asked me what the clearence is ment to be between the piston and the barrel, anyone have any idea what this should be.
    by the way its a Polini Corsa Barrel on a Yamaha Slider (Vertical minerelli AC)
    And the over size is .40 bigger that the original 47.0mm
    Thanks
     
    dezze, Dec 8, 2007
    #1
  2. Haresign

    Haresign New Member

    Messages:
    1,231
    Rides:
    GPR50 + Peugeot 307
    5 or 6 th0

    Thats what mine was done to anyways.
     
    Haresign, Dec 8, 2007
    #2
  3. MiNoR cOnFuSiOn

    MiNoR cOnFuSiOn Administrator Staff Member

    Messages:
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    et2 monster
    erm, same increase as the bore on the piston, so if your goingout .40 you need a piston .40 bigger obv. there will be a set size of oversized piston avalable for the .40 overbore anyway so just order the next size up
     
    MiNoR cOnFuSiOn, Dec 8, 2007
    #3
  4. dezze

    dezze Member

    Messages:
    148
    yeah ive allready got the oversize piston but i just want to know what the clearence needs to be between the piston and the barrel ? should 5-6 thou be cool ?
    and how does that look like a in number form ?
    just want to know exactly what im doing, dont want to get it wrong !!!
    safe
     
    dezze, Dec 8, 2007
    #4
  5. MiNoR cOnFuSiOn

    MiNoR cOnFuSiOn Administrator Staff Member

    Messages:
    14,276
    Rides:
    et2 monster
    tbh its an iron barrel, whoever is overboring it should know. if they dont I WOULDENT TRUST EM WITH IT
     
    MiNoR cOnFuSiOn, Dec 8, 2007
    #5

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