02 800r help.

[Gaderunner]

I have a 2002 Renegade 800r that has good low end power but stops at about 40mph and won't increase speed any farther. Seems to have good compression, not smoking any and has spark to both plugs.
What should I check next?
Thanks for your help.

 

[Red-eye]

Both clutches

 

[winter brew]

What rpm is it running? Any other details?

 

[Gaderunner]

rpms

It is running at about 6000 rpm,

 

[winter brew]

I would start with exhaust valve function and clutches. Broken clutch spring? Excessive wear/binding?