New to gas gas. Ec300 doesn?t scream

[Lozarus]

Hiya new to gas gas. Only had 250f?s in the past and 125
2 strokes..
Got a 2010 Ec300. Just had a new top end. Load of compression and runs well.
Has loads of bottom end but just seems to lack top end like it doesn?t scream. Is this just a characteristic of this engine? I think it?s running pretty rich so am gonna do the jetting. Any particulatar brand to go for or are jets jets?I?ve checked the power valve all ok. Repacked exhaust etc
It feels like apart from the bottom end kick in the first few gears that it runs out of puff feels like a cr125 top end. Any pointers would be appreciated.
My understanding is That I can lift adjust the height of the main jet to lean it out some? At the moment if i lean the bike Right over fuel doesn?t come out of the overflow
Thanks for your help