Valve TDC question with picture
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  1. #1
    Senior Member Snake2715's Avatar
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    Ok I have a quick question. Reading the various threads on this. I am attempting it on my friends bike.





    I am curious as to what TDC is actually. I have read various threads that say there will be a "T" present... in this thread the OP mentioned he had a line dash line... kind of like an H:



    https://tw200forum.com/forums/43540/ShowPost.aspx



    I am in my friends 92 TW200 I see both a single line and then a T, and then following that I see a line dash line "H".



    Line then "T"









    "H"









    Both are when the piston as at the top as I have the sparkplug out with a flashlight.





    The "H" shape I can fit a .003 feeler between the valve.. on the "T" I cannot get a .003 feeler through.





    I am leaning toward the "H" being TDC.. if thats so do I just go to the center of the "H"?

  2. #2
    Senior Member pgilles's Avatar
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    ***Edited because of bad information
    Sold bike.



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  3. #3
    Senior Member B-dub's Avatar
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    On page 50 (Chapter 3, Page 4) of the TW200 main manual found here it says it should be aligned with the T while on the compression stroke.
    My handle is B-dub, I ride a T-dub, and drive a V-dub.

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  5. #4
    Banned qwerty's Avatar
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    Align the T. If both rockers wiggle, that is TDC in compression. If valves are tight, that is TDC on overlap.




  6. #5
    Senior Member Snake2715's Avatar
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    Quote Originally Posted by qwerty View Post
    Align the T. If both rockers wiggle, that is TDC in compression. If valves are tight, that is TDC on overlap.
    On the T last night they were tight. Should I spin 1 rotation to the T again and recheck? Or is it possible someone else adjusted to the H?



    I will rotate 360 degrees and recheck at the T.



    I will download the manual tonight and take a look.

  7. #6
    Banned qwerty's Avatar
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    If they were both tight, you were on overlap. Rotate crank 360*. If you've a messed up adjustment and rockers are loose after rotating it is still easy to find the correct point in the cycle for adjustment.



    Turn the cranckshaft counterclockwise while watching the exhaust valve. The exhaust valve goes down, then up, theT goes by just before the valve is all the way up, stop at the T next time it comes around.



    Another way to remember is intake-T-exhaust. You want the T between after the intake valve moves and before the exhaust valve moves.



    If you are on the T after the exhaust and brgotr thr intake the crank is 360* out.




  8. #7
    Senior Member TW_in_BC's Avatar
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    Remove both valve covers and engine plugs.

    Turn engine CCW while watching the valves...when the intake valve OPENS, this is the beginning of the intake stroke. Then it will close, marking the start of the compression stroke.

    It is at this point that you want TDC (I believe Qwerty mentioned a method using a pencil inserted into the spark plug hole) then note which marking is used, for future reference.
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  9. #8
    Member dmathia's Avatar
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    Quote Originally Posted by TW_in_BC View Post
    Remove both valve covers and engine plugs.

    Turn engine CCW while watching the valves...when the intake valve OPENS, this is the beginning of the intake stroke. Then it will close, marking the start of the compression stroke.

    It is at this point that you want TDC (I believe Qwerty mentioned a method using a pencil inserted into the spark plug hole) then note which marking is used, for future reference.


    Pencil is OK. I would use a straw just to be careful. There will be a few degrees of rotation where the piston seems stationary. TDC is the center of that dead spot, no matter what mark is showing. On mine, the mark was not accurate. Also, when it is TDC on the exhaust stroke, the valves will be in "overlap". The exhaust will just be closing and the intake will just be opening at TDC. It's a good way to check your cam timing. The cam should be centered in overlap at exhaust TDC. Rocking the engine crankshaft forward and back will check chain tension. A slack chain will cause a lag in the movement of the camshaft when you change directions.
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