Thread: Piston Stop

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  1. #1
    Member Double Trouble's Avatar
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    Praying Piston Stop

    Just received the evinrude piston stop.how do I set the depth of the plunger to find top dead center of the #1 piston?

    Thanks for the help
    John
    Twin 200 2005 Mercury Optimax Engines
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    #2
    One most engines, you would use a degree wheel, or a graduated ruler on the flywheel, and a fixed pointer.
    Rotate the engine until the piston comes up against the piston stop, and note the position on the degree wheel/flywheel. Rotate the engine in the opposite direction until the piston hits the stop again, and note the position on the degree wheel/flywheel. Remove the stop. Halfway between these two points is TDC.
    Perhaps Evinrude has a different, motor specific way to do it, but that's the method in a nutshell.

  3. Member Double Trouble's Avatar
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    #3
    Quote Originally Posted by Nova Kaw 650 View Post
    One most engines, you would use a degree wheel, or a graduated ruler on the flywheel, and a fixed pointer.
    Rotate the engine until the piston comes up against the piston stop, and note the position on the degree wheel/flywheel. Rotate the engine in the opposite direction until the piston hits the stop again, and note the position on the degree wheel/flywheel. Remove the stop. Halfway between these two points is TDC.
    Perhaps Evinrude has a different, motor specific way to do it, but that's the method in a nutshell.
    I know the method what I need to know is how deep to set the piston stop.Thanks anyway.
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  4. Member J Risco's Avatar
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    #4
    Quote Originally Posted by Double Trouble View Post
    I know the method what I need to know is how deep to set the piston stop.Thanks anyway.
    That's why the method he described is commonly used, it doesnt matter how deep the stop is set you will always get the same answer, TDC, if you follow the procedure.

    But like he also said, OMC might use a different method, I forget as the only time I checked my old one was years ago
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  5. Ohio Fishing Reports Moderator omcforever's Avatar
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    #5
    Never turn the motor(outboard) the opposite direction. There is a specified way described in all OMC service and repair manuals. Not the same as a 4 stroke car motor. The only time you can do it backwards is when the powerhead is not attached to the mid and lower or the lower unit and water pump assembly are removed. Go by what your OMC service manual says in the synchronization and timing section..

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  6. Ohio Fishing Reports Moderator omcforever's Avatar
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    #6
    Remove sparkplugs. Turn motor by hand untill piston #1 has moved 1/2 " down past TDC. Insert piston stop tool, and adjust screw till it touches piston top. Lock Screw, and holding piston back against stop tool, make a pencil park on flywheel exactly at pionter. Turn motor clockwise till piston touches tool again, make another mark. Using a Flexible Scale, mark exact center between the two marks on flywheel. Turn motor to pionter is against the new center mark. Adjust pionter position to point against the original TDC mark in flywheel. Pointer now is correct/TDC. This is the common way but be sure to check the manual for your specified motor.****Never turn counter clockwise/backwards from normal rotation****

    Age and treachery will always overcome youth and skill !!

  7. Member J Risco's Avatar
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    #7
    Quote Originally Posted by omcforever View Post
    Never turn the motor(outboard) the opposite direction. There is a specified way described in all OMC service and repair manuals. Not the same as a 4 stroke car motor. The only time you can do it backwards is when the powerhead is not attached to the mid and lower or the lower unit and water pump assembly are removed. Go by what your OMC service manual says in the synchronization and timing section..
    Good info here. Wish I would have kept my Fast Strike service manual. Someone needed it after I sold mine so I sold it to him cheap, dumb decision haha
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  8. Member Double Trouble's Avatar
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    #8
    Thanks every one thats what I needed to know!
    Twin 200 2005 Mercury Optimax Engines
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    #9
    Quote Originally Posted by omcforever View Post
    Never turn the motor(outboard) the opposite direction. There is a specified way described in all OMC service and repair manuals. Not the same as a 4 stroke car motor. The only time you can do it backwards is when the powerhead is not attached to the mid and lower or the lower unit and water pump assembly are removed. Go by what your OMC service manual says in the synchronization and timing section..
    Good info there ^^^^ I didn't consider the water pump impeller.