2005 Yamaha RX one lacking power on top end

[Nick C123]

Not sure of its use exactly. Just know my 08 Kodiak 450's carb cap has the recessed area for the o-ring but does NOT have the o-ring.

Interesting strange design

 

[STAIN]

Now that I'm thinking about it, I towed my brother home, and then after it started acting this way

Did you smoke the belt when towing?
Towing, especially done by the inexperienced, will destroy a belt FAST

 

[maim]

also check the clutch components. a new primary spring is a good idea as it sat under load for all these years witch makes it go weak.