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Thread: 250R Long rod

  1. #1
    Tecate Karl is offline Check my feedback before buying from me First time rider
    Join Date
    Feb 2010
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    Virginia Beach, Virginia, United States
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    163

    250R Long rod

    So I'm new to this 250r long rod/short rod thing. So I am wondering what the real diffrence is and what are the pros and cons of each I'm getting ready to put a crank in a 85R and am wondering what would be the better choice thanks.

  2. #2
    Join Date
    Aug 2008
    Location
    OK
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    5,450
    My question is if you run a trx long rod motor with the spacer can you still use the atc250r head stay? Or is that why they sell the cool heads without the head stay?
    Rides:
    1986 ATC250R (sectional pipe and Klemm Research silencer)
    1986 ATC250R (Desert Bike, WAX-ON seat, Dual Cibie lights, Steering Stabilizer)
    1979 ATC110 (Bandito frame and forks, Turbo wheels, disc braked)
    1982 ATC70 (Lifan manual 125)
    1987 LT80 (piped, widened)


    My feedback thread
    http://www.3wheelerworld.com/showthr...ack-for-dcreel

    RIP Trace.. Godspeed.

  3. #3
    Tecate Karl is offline Check my feedback before buying from me First time rider
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    Feb 2010
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    Virginia Beach, Virginia, United States
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    163
    well Doug good Question I'm really hopping someone jumps in hear and enlightens us.

  4. #4
    200xranger's Avatar
    200xranger is offline At The Back Of The Pack Arm chair racerFirst time rider
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    Jun 2007
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    St. Louis
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    207
    i used a long rod with an 86 piston and spacer plate and the motor mount for the head lined up and i too have an 85 atc. dont ask me how but i did no mods to it for it to bolt up. from what i read when i did mine it decreases the crank volume so the motor doesnt rev as quick and gives you more low end.
    Three Wheels Are Better Than Four!!
    My Rides:
    85 250r atc
    85 tri z
    2012 honda rincon 680

  5. #5
    Join Date
    Nov 2006
    Location
    southern oregon
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    2,338
    a spacer and longrod increases the case volume
    2-stroke lover

  6. #6
    Join Date
    Jun 2010
    Location
    House Springs MO
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    5,496
    I have mixed feelings about the long rod. I have never ridden a long rod engine that impressed me. I like the quick hit and reving of the short rod engine. This is personal preference though and others might like a smooth power delivery. I like a light switch powerband.

    Honda went to the long rod in '87 to improve low end torque on the TRX models with the extra weight of the fourth wheel.

    My opinion is that the trike doesn't need to worry about the torque because of how light it is and if it was me and I had to rebuild a short rod engine it would go back as a short rod crank.

    As far as the head stay I have heard some say it will and some say it will not work. I think that most that do not work are the stroker guys with thicker plates.

  7. #7
    Join Date
    Oct 2002
    Location
    Fresno Ca
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    2,695
    The reason for going to the long rod was to decrease piston wear. It makes a less harsh rod angle on the piston.

    There really isnt much performacne difference, (if any)

    When going to a long rod and spacerplate, you increase crankcase volume, Its not that bad on a big engine, but on the small one s it really hurts high rpm's (the dyno's dont show a gain down low, jsut a loss up top) but because there is a loss the bottom feels stronger.

    I personally like the short rods better. But performace wise my fastest engine is a long rod. Go figure.

    As for the head stay, my recomendation is to not run one, i have see them crack, on several engines.

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