Ok reading the manual lightly on page 11-14 is the description of the MAP, since the boths codes 107,108 are refering to electrical problem, there is the option, water got to the sensor and is malfuntioning, or wiring going to the MAP could be damage or not signaling the right amount of volts. you have to check if you recive 5v on the in line and check the ground is good, than check with engine running if there comes some signal from the signal line, so we can figure out if it is the sensor or signal inputs.
The other thing to do is to replace it, but this is a lotery, because it is not the idea of changing all the atv sensors til we fix it.
Those are my best recomendations base on what you are experience till now. I have a PDA manual, but is different from what you have, maybe old model. Read manual electric and troubleshooting, I will do the same and let you now more testing I find.
Hope other members can give some advise?