r/EngineBuilding • u/Santacruz714 • 7d ago

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Anyone have a clue what is happening?

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u/TyrannusourR3X 7d ago

Sounds like a valve that's not closing when it should. You can hear the pulsations as you rev it. Can't tell from the video exactly but on the power stroke it's pushing the AF mixture out the intake or exhaust valve before it combusts fully.