My mechanic in St. Pete (not a Yamaha services centre) can not find the situation. Right here is what has been done to the motor in last couple of months:
drinking water pump
all gas relevant filters
drained VST tank
gas tension examined and very good
Read of related difficulties with F115 on interweb and also adjusted the change posture switch, which appeared to deal with the situation for a single weekend, but trouble is again or did not get preset.
On the lookout for any person who has had the similar trouble.