You're likely going to run into clutch slipping with a full synthetic oil. The 10w40 that is recommended in conventional oil is a non-friction modifier oil. The wet clutches need the friction to maintain good clutch grip. My buddy's dad used M1 in his Intruder to drop the engine temp. It did just that, but he immediately began to get the clutch slip from using a synthetic. 3 oil changes later an he's back to using standard conventional oil.
Just this oil change I used Maxima Racing's Maxum4 Premium 10w40 on recommendation from a good friend who works at a trials bike shop. So far so good. Very firm shifts and the engine is extremely quieter using that oil vs. the KawiChem the dealership used before I bought the bike in the spring.
Maxima Racing Usa - Maxum4 Premium
Next oil change I'm thinking about trying out their Maxum4 Blend:
Maxima Racing Usa - Maxum4 Synthetic Blend