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  1. #1
    elviswongg's Avatar
    Join Date
    Sep 2008

    Compression testing figure


    I know i already ask the question about how much compression should i have on the 250x,

    I heard that the manual state 170 psi, and some rider said to me 145 psi, i guess this figure are with a hot engine , because of the forged piston expension, cause i got 120 psi on 4 cyl on a cold engine,

    With this test and my waranty that is finishing in 2 mounths, i wana make sure that because of gio, that ma rings does there jobs,

    Do you think i ahve a probleme with 120psi cold engine should i go to the dealer???

    Thank you

  2. #2
    Compression results vary. Starter condition, battery state, test method ambient conditions all play a role. 175 PSIG is good. 140 isn't real good, 120 sucks, but did you open the throttle fully while cranking?

  3. #3
    elviswongg's Avatar
    Join Date
    Sep 2008
    yes i just re-test it with a hotter engine and i had 125 psi on all cylinders.

    think i will call on monday to ask the dealer opignion on this ?

  4. #4
    I think your figures will be different from the 170 PSI values you quoted here, those would be for a naturally aspirated engine. I should have read more closely. Yours has a super charger so the compression will be much lower. Best to check the book.

  5. #5

    Join Date
    Mar 2009
    if all 4 cyl's are the same i think u are ok. u really look for one or two that are way lower, that would signify a problem. supercharged engines have lower compression cuz they force another 12 atmospheres down there throat. to much compression = detonation. i think the 09 has a bit more compression than the 07 and 08 but they advanced the igniton and added more lift and duration in the cams on the 09. if all of your cyls are even and ur not getting tons of GIO i think ur OK.

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