mountainmax overrevs

[max]

I have a mountainmax 700 -01.it is stock.When i hit the throttle it revs up to 9000 rpm for two seconds,and then drops to 8500 rpm and stay there.
is something wrong?

 

[MountainMax]

Could be your belt slipping, I bet you are using an 8dn belt right? try the 89l, it's softer but wears faster, it will not slip at start off, I couldn't beleive the difference untill I tried it.