Gilera dna 50 slow

Hi guys new here, recently brought a dna 50. Iv changed rollers (5g) new spark plug, new carb, techni gas qtre exhaust.
Its running so slow. Im getting 40mph on a very slight down hill but up an hill im barely getting 20mph.
It wont even move off till it hits 5000rpm, i am running the standard air filter till my new jets come then ill be using k&n open air filter.
Any ideas whats causing the speed to be so low. I no it wont get massive speed but even if i can get 30-35 uphill it will be great

 

Checked the compression?
Keep the stock airbox

 

Yes theres plenty of compression, and i have the standard airbox on at the minute. Im waiting for 115 and 110 jets to come in post. Gonna try these with the k&n on to see if i can get the speed up hills better but cant see this helping now.
Its getting more top end speed eventually actually hit 50mph yesterday but as soon as it sees any type of hill its just not doing anything

 

Keep the stock airbox though. Its going to give you trouble running a cheap open filter.

 

So thered be no point in upjetting then as i have a 75 in now. Any way i can get the speed uphills better?

 

Try a bigger jet, but keep the airbox

 

Ok cheers, ill keep you updated. Thanks for the help