I use this 13,8 for cruise and 12,7 for full load! Works fine!!Does the sniper have an ethanol content detector? The stoichiometric AFR for normal gas is 14.7. For gas with 10% ethanol is 14.3. With 15% ethanol, its 14.1.
I assume for 27% ethanol, you would be looking at something closer to 13.5 AFR for cruise and 12.5 under load. Does the sniper know what gas you're using? If not, it seems like it would try to run lean.