RGV150 Spluttering between 6000 & 6500 rpm

[puppydog]

Just brought my first bike! It’s a 99 RGV150 and it is perfect for my first bike (I will upgrade in a couple of months)
The only issue I have is that is splutters between 6000 & 6500rpm. Its all good at lower or higher rpm it just as soon as I hit the 6k mark (redline at 10’000).
Now to be honest I do not know very much about bikes but I am pretty sure it shouldn’t do that.
I got the bike off a guy that hadn’t ridden it for about 12 months but it flew through the wof when I took it in. I have replaced the fuel and taken it out for a good 100k run. (total k’s 38000)
Any help/suggestions would be appreciated.

[Racey Rider]

If theres one things I've learned through my years of sorting out two stroke problems, it's -
' The first thing you do, is change to a new spark plug! '

Good luck.

Racey

[Insanity_rules]

Look at the plugs first.

[Chooky]

Air filter.........??

[puppydog]

Plug and air filter are the first 2 things I will try in the morning thanks.

[MDR2]

Too bad the RGV doesn't have Powervalves otherwise this would have been an easy diagnosis

Plug then Carb