Run through your fuel system and make sure all is working properly.
The pump bulb in fuel line should pump fuel one way, not both.
Check and change, if necessary, your water-separating fuel filter (you do have one, don't you?)
Make sure lines are clear (blow out with air compressor).
Check and clean fuel filter under cowling.
Check operation of fuel pump (very easy to change gaskets and diaphragms). Make sure there is no crack in fuel pump housing.
If your motor has carburetors, keep reading. If it is fuel injected, I don't know anything about it.
Clean carburetors, and overhaul if necessary.
If you don't have a service manual for this motor, get one. You can do everything I just said. Make sure simple things are working and set properly to factory specs (which you will find in that manual), such as the float level (and that a float is not punctured), the float needle valves are clean, the air adjust screws are like new (a problem I had), etc.
I kept having trouble with my carbs, and I'd take it in to the Yamaha dealer (I won't say where) and they always did a half-*** job cleaning them, but would charge me about $350 for it. I finally got tired of it and learned how easy it is to do. I can now do it with my eyes closed, literally. I can do my two carbs in two hours or less.