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  1. #1

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    Checking compression

    Sorry if this sounds lame but what's the best way to check compression before I pull the head?


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  3. #3

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    Thanks stock but I've got the tester I just need some pointers like from cold?
    And all plugs out or one at a time ?
    And any other methods used for checking compression.
    I am used to working on 2 strokers and this will be all new to me

  4. #4
    Vern's Avatar
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    Do a search on 'timing' on this forum, you will find a ton of info. From my experience: cold vs hot does not make much difference on this engine, two plugs in seems to yield 10 psi higher readings (no idea why, try it and you will see), make sure your battery is fully charged. 'Normal' range seems to be from 130 - 170+ depending a lot on condition of engine, which cam, cam sprocket slot settings, etc.

  5. #5

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    Quote Originally Posted by Vern View Post
    Do a search on 'timing' on this forum, you will find a ton of info. From my experience: cold vs hot does not make much difference on this engine, two plugs in seems to yield 10 psi higher readings (no idea why, try it and you will see), make sure your battery is fully charged. 'Normal' range seems to be from 130 - 170+ depending a lot on condition of engine, which cam, cam sprocket slot settings, etc.
    Thanks vern I did read a lot on timeings and on some they say hold throttle at wot when doing a compression check , my engine won't crank if I hold it at wot. This was the confusing part for me so I thought I'd try and get an educated opinion.
    Cheers bro

  6. #6
    Vern's Avatar
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    Wow, strange ... holding the throttle WOT usually is what you want to do if you want to spin over the motor but not start it. Strange that yours won't crank when holding WOT, that is unusual. Just disconnect all coil wires and test that way then.

  7. #7

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    Quote Originally Posted by Vern View Post
    Wow, strange ... holding the throttle WOT usually is what you want to do if you want to spin over the motor but not start it. Strange that yours won't crank when holding WOT, that is unusual. Just disconnect all coil wires and test that way then.
    That's what I thought I read something of a anti flood device. Ok so it's just to kill the power to the coils (normaly)I thought I might have had something to do with the compression readings
    Exelent vern thanks

  8. #8
    West Texas RXP skoepp's Avatar
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    Quote Originally Posted by ski33 View Post
    Sorry if this sounds lame but what's the best way to check compression before I pull the head?
    Warm motor
    On charger
    Plugs in
    Disconnect fuel pump
    wot throttle

  9. #9
    West Texas RXP skoepp's Avatar
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    Quote Originally Posted by ski33 View Post
    Thanks vern I did read a lot on timeings and on some they say hold throttle at wot when doing a compression check , my engine won't crank if I hold it at wot. This was the confusing part for me so I thought I'd try and get an educated opinion.
    Cheers bro
    Your motor should turn over regardless of throttle position.

  10. #10
    SplishSplash's Avatar
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    Quote Originally Posted by skoepp View Post
    Warm motor
    On charger
    Plugs in
    Disconnect fuel pump
    wot throttle

    I think if your holding wot, then no need to disconnect fuel pump cause spark and injectors do not operate at wot crank.

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