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FZR250 Big bore?

Discussion in 'Yamaha 250cc In-Line 4's' started by Linkin, Jan 17, 2015.

  1. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Linkin, Jan 17, 2015
    #1
  2. Th3_Huntsman

    Th3_Huntsman Senior Member Contributing Member

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    Pretty sure those are just if you need to bore and honey the cylinders. Not for more power or anything. Just to rectify a problem in the lining.
     
    Th3_Huntsman, Jan 17, 2015
    #2
  3. Mclaren

    Mclaren Well-Known Member Contributing Member

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    If u want power u want better compression
     
    Mclaren, Jan 17, 2015
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  4. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    Bigger bore will give better compression with standard piston height.
    Bit pricey per piston.
     
    Murdo, Jan 17, 2015
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  5. cal

    cal Well-Known Member Premium Member

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    your bike will run/go heaps better with new rings and pistons, should restore any lost compression. would be good to have a set in the shed for when she starts burning oil :thumb_ups:
     
    cal, Jan 18, 2015
    #5
  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    If you do go down this path, I would recommend at least weighing the piston and gudgeon pin and compare to standard. The pin in that image looks very thick, like it is a piece of standard ground bar. The extra weight can lead to broken rods quite quickly. Secondly, replace the circlips with genuine items.
     
    • Like Like x 2
    maelstrom, Jan 18, 2015
    #6
  7. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Not likely that I will, was just talking with @Grasshopper last night about ways to improve the FZR. Bigger bores, polish & hone etc
     
    Linkin, Jan 18, 2015
    #7
  8. CompeyRom

    CompeyRom Active Member

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    Those sets look sketchy! Personally, I woudn't like chinese parts at 16.000rpms in my engine.
     
    CompeyRom, Jan 31, 2015
    #8
  9. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Yeah Compey you are right, but deep inside we all hope that they are ok because genuine costs the planet :)
     
    maelstrom, Jan 31, 2015
    #9

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