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Thread: 250R Compression

  1. 03-30-2005, 09:49 PM #1
    Fox250R's Avatar
    Fox250R
    Fox250R is offline Power User Roostin Away
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    250R Compression

    My R has 190 psi......Is this too much or not enough? And how much compression does a stock 85-86 250R have?
    1986 ATC 250R
    Ported w/ Cool head
    LED pipe and silencer.
    Vforce3
    Keihin PWK 38mm
    Works Ultra Cross Shock
    LSR +2 Axle
    American Star Racing +4 Swinger
    LED Intake
    Hi-Flite desert seat
    OEM clutch 89 upgrade
    2021 YFZ450Rse Rossier R5 Titanium Header AIS Delete FCI Vortex ECU

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  2. 03-30-2005, 10:00 PM #2
    lisnup65
    lisnup65 is offline Just Too Addicted Arm chair racerJust too addicted
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    190 is actually high. It requires the use of preminum fuel and is on the verge of needing a even higher octane. My 85 250R has 145psi.
    Signature:
    1985 ATC350X
    1986 TRX-250R(Soon to be an 87)
    2001 Polaris Scrambler 90
    2004 Arctic Cat DVX400
    2003 Yamaha Blaster
    2005 YFZ450
    Rip: To many to list........
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  3. 03-30-2005, 10:08 PM #3
    deathman53
    deathman53 is offline Power User Teaching quads a lesson
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    a stock 250r has about 180 on a atc gasket and about 165 on trx gasket, my atc was running 220 psi and that is with a atc gasket, I never put a cr gasket in. Most cr gasket motors with a coolhead and 18cc dome run at 250 psi. I use race gas, so its no big deal. If you want, get a 89 head, its cut thicker as honda lowered the compression for the 89 year(in 88 people apparently were having problems starting the bikes, becuase of the compression), each year head has a different dome and different compression. I think the atc's had the most, then the quads got less and in 89 it dropped more.
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  4. 03-31-2005, 01:18 AM #4
    Fox250R's Avatar
    Fox250R
    Fox250R is offline Power User Roostin Away
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    cool thanks for the info...
    1986 ATC 250R
    Ported w/ Cool head
    LED pipe and silencer.
    Vforce3
    Keihin PWK 38mm
    Works Ultra Cross Shock
    LSR +2 Axle
    American Star Racing +4 Swinger
    LED Intake
    Hi-Flite desert seat
    OEM clutch 89 upgrade
    2021 YFZ450Rse Rossier R5 Titanium Header AIS Delete FCI Vortex ECU

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  5. 03-31-2005, 09:19 PM #5
    md1985250r's Avatar
    md1985250r
    md1985250r is offline Just Too Addicted Arm chair racerJust too addicted
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    Stock engine 85R........170.7-199.1 psi is factory spec on compression. GREG



    ps...lisnup..you need some work done my friend.Good luck
    1985 ATC 250R
    2006 TRX450ER
    RIDE RED...IS THERE ANYTHING ELSE??????????
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  6. 04-01-2005, 04:07 AM #6
    Fox250R's Avatar
    Fox250R
    Fox250R is offline Power User Roostin Away
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    so i guess 190 is pretty close then...Cool,Thanks for the info guys...
    1986 ATC 250R
    Ported w/ Cool head
    LED pipe and silencer.
    Vforce3
    Keihin PWK 38mm
    Works Ultra Cross Shock
    LSR +2 Axle
    American Star Racing +4 Swinger
    LED Intake
    Hi-Flite desert seat
    OEM clutch 89 upgrade
    2021 YFZ450Rse Rossier R5 Titanium Header AIS Delete FCI Vortex ECU

    Reply With Quote Reply With Quote
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