In the process if r&r ing the HEs, I got a chance to loot at the exhaust side of the head and found a build-up of carbon. May not be an unusual amount for a 90k 914 but wondering what fuel additives you have had success with in carbon removal?

Tektron

Someone on a Honda forum (redpepperracing.com) mentioned seafoam. Not an endorsement, just passing along the reference.

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