Walbro was reported to not(!) take well the Methanol/Nitro fuels on its membranes
and also on other parts even if you wahs it after the flights everyday with gasoline
it will still brake down. In general seems anything desinged to resist gas does not
resist Methanol/Nitro and the Other Way Arround. Well, the time matters indeed,
it is maybe OK for couple days prior destriction.