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Thread: No compression, valves????

  1. #1
    Join Date
    Dec 2013
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    No compression, valves????

    Hey guys i have a 85 200x that was running fine one kick and it would start right up but it ticked a little bit and i thought adjusting the valves might take some of it out. So i took the spark plug out, got it to tdc from what i could tell. I couldent really find any marking on the stator so i used a screwdriver to see when the piston was all the way up. It seemed like the intake valve was much tighter than the exhaust and had very little of a gap so i loosened it maybe 1/2 turn out, tightened it up and put it back together. Also i checked the exhaust gap and it was slightly loose at .004. Went to start the bike and the first few kicks it felt fine even tried to start once but a few kicks later it just lost compression. Could the intake gap be to big and it has no compression now or whats the deal? I hope i didnt hurt anything

  2. #2
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    Sounds like you may have checked it on top dead center combustion, instead of top dead center compression.

    STOP.
    GET A SERVICE MANUAL.

  3. #3
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    And FYI, four stroke overhead cam engines "tick a little bit." That's normal.

  4. #4
    Join Date
    Dec 2013
    Location
    Ft lauderdale, FL
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    Could that hurt the motor by any chance? It felt good at first kicking it over then just lost it

  5. #5
    Join Date
    Mar 2010
    Location
    Pacific NW
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    4,255
    My thought?
    Probably wrong?
    But if you found a top center and the rocker had play and you changed it a tiny bit
    it shouldn't have killed anything.
    Did you tighten the locknut? or did the phone ring or something.
    can you click on
    service manual
    ?

    Both cam lobes down is what stroke?
    Both up?
    I forget.
    Nice to find the tdc marks and do it right.
    Now does the cam go around 2x for every crank revolution? or is it the other way around?

    Not being a wise^%$, just stuff I'd expect to see on a test that I'd probably fail.

    ***Could the intake gap be to big and it has no compression now or whats the deal? I hope i didnt hurt anything

    I'd guess that intake too loose just wouldn't open.
    Too tight and holding open would lose compression.
    Do those engines have a compression release? usually tied to a valve to hang it open a little for a bit.

    I'd better just stop talking.
    Good luck and let us know if you can't dl the manual or try the search key for
    valve adjust.
    You should get tons of posts.

  6. #6
    Join Date
    Dec 2013
    Location
    Ft lauderdale, FL
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    I went to http://www.oscarmayer.net/atc/manuals/ for the manual i just couldent find the T mark im just gonna try again tommorow and see where it takes me. Just hope i didnt hurt anything i wanna take it out this weekend

  7. #7
    Join Date
    Mar 2010
    Location
    Slidell, LA
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    4,738
    set both valves at .08MM or .003 Inches.
    Feedback for yaegerb: Click Here

    Need something blasted or polished or both? Send me a PM

  8. #8
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    One failsafe method for finding tdcc on any overhead cam four stroke thumper (one cylinder) is to watch the intake rocker as you rotate the crank. Rocker goes down, intake valve opens, rocker comes back up and stops, now you are on the compression stroke. At this point just continue rotating until the timing marks, which can be VERY hard to see on the X, line up.

  9. #9
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    Quote Originally Posted by tri again View Post
    Both cam lobes down is what stroke?
    Both up?
    I forget.
    Nice to find the tdc marks and do it right.
    Now does the cam go around 2x for every crank revolution? or is it the other way around?

    Not being a wise^%$, just stuff I'd expect to see on a test that I'd probably fail.

    I'd better just stop talking.
    Lol maybe...

  10. #10
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    Dec 2013
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    [QUOTE=DohcBikes;1275917 At this point just continue rotating until the timing marks, which can be VERY hard to see on the X, line up.[/QUOTE]

    It sure is

  11. #11
    Join Date
    Dec 2013
    Location
    Ft lauderdale, FL
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    Well i finally found the T mark, god is it small. Turns out i tightened it to much on the wrong stroke. Put it at tdc and did the intake valve now it has good compression again. Thanks for the help guys

  12. #12
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    So is she running?

  13. #13
    Join Date
    Dec 2013
    Location
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    Yep back to a one kick bike, and because its usually 70 degrees and up here i never have to give it choke it just fires right up. Gonna ride it over the weekend and see how it does.

  14. #14
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    Awesome. Good work.

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