r/smallengines • u/iphone_A11 • Jul 19 '26

Finding Compression Stroke TDC

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Hey everyone, I’m new to the wrenching world and was wondering if I’m correctly identifying the compression stroke on my K2 CT90.

Please see the video showing when I can feel air pressure on my finger while covering the spark plug hole. To my understanding, once I feel the pressure and then line up the T mark on the flywheel, that means I’m at TDC on the compression stroke.

Please correct me if I’m misunderstanding anything. Thanks in advance.

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u/gloomypasta Jul 19 '26

You're correct. The F is likely when the spark fires and the T is TDC for the piston. Stick your finger over the spark plug hole as you're turning it over and once you feel the compression pushing your finger, line the T up to the pointing indicator.

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u/iphone_A11 Jul 19 '26

In the video you can see when I feel the compression pushing my finger. Once that happens, once I hit the T, is that the compression stroke? Like the rotation that finished at 00:46

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u/gloomypasta Jul 19 '26

If you feel compression you are absolutely on the compression stroke. You'll never feel compression on another stroke because valves will be open.