Bogging on top speed?

Hey guys,
Lately I noticed that my bike isn't running smoothly as it did, on top speed it starts cutting out and I'm forced to let go of the throttle. It also takes a lot longer to get to top speed, feels like its too rich or something...What can cause this? (Maybe the weather? It got very hot here lately)

Spec:
Typhoon 2006.
S6 sport pro mk2 70c.
S6 pro replica pipe.
Polini variator.
Motoforce 17.5 carburetor (UpJ to 72).
S6 double layer filter in the original air box.


Thanks.

 

It could be the weather, my rox runs like a pig when the air temperature rises. It messes up the mixture then runs fime when it's cooler.

 

So what would you recommend, making it leaner or richer?

 

Hot air less dense runs rich. cold air more dense runs lean and quick.

 

Makes sense, thanks!