Hi,
Your success with the YS-91ac is admirable,all the more so in light of my lack of success with this powerful little screamer. To date, I have reset the tappet clearances and replaced all gaskets. I cannot seem to achieve a balanced high end with a steady low end. I use PowerMaster YS fuel and am running with an APC 14X6 prop and follow the engine instructions. Do you reset the regulator adjustment? Suggestions would be very appreciated!
Best Wishes,
Jim