I recently had a valve issue on the RANS's Rotax. 20 over 85! When I took the head to "my" mechanic, He turned it upside down, squirted some brake cleaner, or maybe it was carb cleaner, (not important what it was, something he had handy and that stayed in a fluid state for a bit) and when it ran out the intake valve, the mystery was solved. He popped the valve out, and discovered the factory in Austria had missed a step, the valve seat wasn't ground [down deep enough. So, little sealing area, thus the leak. With no damage to the valve, he quickly ground the seat down to the correct depth and angle, put the valve back in, did the leak test, and I was good to go. Total elapsed time, both of us BSing the entire time, was 20 minutes. it was worth the 4 hour drive (1 way) to Elko, got it fixed plus got educated. Hal Stockman, mechanic virtuoso!