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I generally find TDC on the compression stroke by watching the intake valve close then lining the T mark.

But I recently did a top end rebuild on a 79 CM185 and as per the instructions in the manual , I backed off all the rocker screws so I could torque the cam holders down.

Would I have to find it based on the cam lobe position now? Since the rockers aren't being affected by the cam lobes? I hope this makes sense.
 

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Adjust all four valves at tdc. Now turn the engine over 1 turn, one set of rockers will be very loose and will need to be adjusted again. That cylinder is on the compression stroke.
 

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Look at the end of the cam on the left side. See that notch? At TDC it will either face forwards or backwards. Backwards means you adjust the left valves, forward means right side.
 

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what's wrong with sticking a long screw driver in to find out where the compression stroke is? It seems to me that would be a lot easier than trying to remember which cam lobe is facing where.
 

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The screwdriver will only tell you when the piston is at the top of it's stroke, not whether it's on the compression stroke or the exhaust stroke.
 

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Well by watching the screw driver move up as you turn the crank shaft you would know it's on the compression stroke no?
 

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True but along with the screw driver to find TDC I usually just put my thumb over the plug hole and can tell when it's on compression. Since I'm too lazy to take the head covers off (not a lot of room without taking off the carbs as well) just to check timing LOL
 
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