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Thread: CT Big Bore...Which one do I have??

  1. #1
    Join Date
    Jan 2003
    Location
    Midland, MI
    Posts
    451

    CT Big Bore...Which one do I have??

    Just bought a 250R with a CT big bore. Has the pro-x ct non-powervalve cylinder, but the guy did not know what one it was. I'm assuming it's a 310, 330, or 350, but I don't know for sure....Is there a way I can verify this without pulling the dang thing apart? Thanks! It rips by the way.
    04 450R
    02 300EX
    86 250R

  2. #2
    Join Date
    Feb 2006
    Location
    MA
    Posts
    181
    no there really isnt a way to tell without pulling it apart unless it is grooved somewhere on the cylinder. my ESR cylinder says the size right on the bottom of the intake port, i dont know if CT has that grooved on their cylinders too but its worth a look
    '87 250r getting a full rebuild


    2005 CR250r

  3. #3
    Join Date
    Oct 2004
    Location
    Las Vegas, NV
    Posts
    1,110
    I do not think there is anyway you can tell without at least pulling the cylinder head off to measure the bore. I have had both a CT Racing 330 kit and a 350 kit, there was no way to tell them apart other then measuring the bore.

    Doug
    2004 TRX450R, 2008 TRX700XX
    (BITD #639 Quad Ironman Expert)

    2013 sponsors: Teixeiratech.com, Motowoz.com, Dirttricks.com, Snailmotorsports.com, My bank account.

    2008 TRX700XX
    2005 TRX450R
    1986 TRX250R

  4. #4
    Join Date
    Jan 2003
    Location
    Midland, MI
    Posts
    451
    OK guys. I looked down my spark plug hole after taking half the dang quad apart so I could see down it.

    The piston is 80.44 MM and the other number says 8944. This is freaking huge. Anybody take a guess as to what motor I have? The power feels like a CR500 on steroids.

    Need help!!! Thanks.
    04 450R
    02 300EX
    86 250R

  5. #5
    Join Date
    May 2006
    Location
    elkview, wv
    Posts
    331
    Originally posted by cracer250
    OK guys. I looked down my spark plug hole after taking half the dang quad apart so I could see down it.

    The piston is 80.44 MM and the other number says 8944. This is freaking huge. Anybody take a guess as to what motor I have? The power feels like a CR500 on steroids.

    Need help!!! Thanks .
    Take a pic and it will be easy to ID.

  6. #6
    Join Date
    Jan 2003
    Location
    Midland, MI
    Posts
    451
    Don't know how it's easy to id by a picture, but here you go.
    Attached Images Attached Images
    04 450R
    02 300EX
    86 250R

  7. #7
    Join Date
    Jan 2003
    Location
    Midland, MI
    Posts
    451
    Another
    Attached Images Attached Images
    04 450R
    02 300EX
    86 250R

  8. #8
    Join Date
    Jan 2003
    Location
    Midland, MI
    Posts
    451
    last one.. HELP!!!
    Attached Images Attached Images
    04 450R
    02 300EX
    86 250R

  9. #9
    Join Date
    Apr 2005
    Posts
    121
    That is a 350
    later
    adam
    87 trx 250r
    holeshott Hds
    maier plastics
    CR 250 ignition
    CPI big bore pipe
    rad valve
    air striker carb
    K&N filter
    NPRD/C-Leigh 350 power valve
    ricky stator arms
    works pro series shocks

    And yes it is really fast
    Kicken a@@ with mixed gas!

  10. #10
    Join Date
    Jan 2003
    Location
    Midland, MI
    Posts
    451
    Thanks for the help. Can you tell me how you came to that conclusion so I can gain some knowledge of this engine?

    Thank you.
    04 450R
    02 300EX
    86 250R

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